Find, fix and prevent vulnerabilities in your code.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Uncontrolled Memory Allocation. Nokogiri bundles the libxslt C library, that has been recently discovered to have vulnerabilities.

CVE-2019-13117 In numbers.c in libxslt 1.1.33, an xsl:number with certain format strings could lead to a uninitialized read in xsltNumberFormatInsertNumbers. This could allow an attacker to discern whether a byte on the stack contains the characters A, a, I, i, or 0, or any other character.

CVE-2019-13118 In numbers.c in libxslt 1.1.33, a type holding grouping characters of an xsl:number instruction was too narrow and an invalid character/length combination could be passed to xsltNumberFormatDecimal, leading to a read of uninitialized stack data

CVE-2019-18197 In xsltCopyText in transform.c in libxslt 1.1.33, a pointer variable isn't reset under certain circumstances. If the relevant memory area happened to be freed and reused in a certain way, a bounds check could fail and memory outside a buffer could be written to, or uninitialized data could be disclosed.

Remediation

Upgrade nokogiri to version 1.10.5 or higher.

References

• GitHub Commit
• GitHub Commit
• GitHub Issue
• libxslt patch (CVE-2019-13117)
• libxslt patch (CVE-2019-13118)
• libxslt patch (CVE-2019-18197)

Overview

nokogiri (鋸) is an HTML, XML, SAX, and Reader parser, with the ability to search documents via XPath or CSS3 selectors.

Affected versions of the package are vulnerable to Arbitrary Code Execution or a Denial of Service (memory corruption) via a crafted web site. Nokogiri bundles the libxslt library, which is vulnerable in versions below 3.

Denial of Service (DoS) - CVE-2016-4738

libxslt allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site.

Arbitrary Code Execution - CVE-2017-5029

The xsltAddTextString function in transform.c in libxslt, lacked a check for integer overflow during a size calculation. This allowed a remote attacker to perform an out of bounds memory write via a crafted HTML page.

Remediation

Upgrade nokogiri to version 1.7.2 or higher.

References

• GitHub Issue
• GitHub Commit

Overview

nokogiri is an HTML, XML, SAX, and Reader parser. Among Nokogiri's features is the ability to search documents via XPath or CSS3 selectors.

Affected versions of this package are vulnerable to Denial of Service (DoS) due to using vulnerable version of libxml2 which incorrectly handled certain fields. An attacker could use this issue with specially constructed XML data to cause libxml2 to consume resources, leading to a denial of service.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade nokogiri to version 1.8.2 or higher.

References

• Git Hub Issue
• Bugzilla Bug

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Expired Pointer Dereference via 'xmlSchematronGetNode()` function in Schematron validator. An attacker can cause a crash or execute arbitrary code by triggering use of freed memory.

Remediation

Upgrade nokogiri to version 1.18.9 or higher.

References

• Fix Commit
• Red Hat Bugzilla Bug

Overview

nokogiri (鋸) is an HTML, XML, SAX, and Reader parser, with the ability to search documents via XPath or CSS3 selectors.

Affected versions of the package are vulnerable to Out of Bounds Memory Write. Nokogiri bundles the libxslt library, which is vulnerable in versions below 3. The xsltAddTextString function in transform.c lacked a check for integer overflow during a size calculation, which allowed a remote attacker to perform an out of bounds memory write via a crafted HTML page.

Remediation

Upgrade nokogiri to version 1.7.2 or higher.

References

• GitHub Issue
• GitHub Commit

Overview

nokogiri (鋸) is an HTML, XML, SAX, and Reader parser, with the ability to search documents via XPath or CSS3 selectors.

Affected versions of the package are vulnerable to many vulnerabilities, including Arbitrary Code Execution and Denial of Service (DoS), and Sensitive Information Exposure. Nokogiri bundles the libxml2 library, which is vulnerable in versions below 2.9.5.

The CVEs assigned to the vulnerabilities are:

CVE-2017-0663

It was discovered that a type confusion error existed in libxml2. An attacker could use this to specially construct XML data that could cause a denial of service or possibly execute arbitrary code.

CVE-2017-7375

It was discovered that libxml2 did not properly validate parsed entity references. An attacker could use this to specially construct XML data that could expose sensitive information.

CVE-2017-7376

It was discovered that a buffer overflow existed in libxml2 when handling HTTP redirects. An attacker could use this to specially construct XML data that could cause a denial of service or possibly execute arbitrary code.

CVE-2017-9047

Marcel Böhme and Van-Thuan Pham discovered a buffer overflow in libxml2 when handling elements. An attacker could use this to specially construct XML data that could cause a denial of service or possibly execute arbitrary code.

CVE-2017-9048

Marcel Böhme and Van-Thuan Pham discovered a buffer overread in libxml2 when handling elements. An attacker could use this to specially construct XML data that could cause a denial of service.

CVE-2017-9049, CVE-2017-9050

Marcel Böhme and Van-Thuan Pham discovered multiple buffer overreads in libxml2 when handling parameter-entity references. An attacker could use these to specially construct XML data that could cause a denial of service.

Remediation

Upgrade nokogiri to version 1.8.1 or higher.

References

• GitHub Issue
• Ubuntu Security Notice

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Expired Pointer Dereference due to a null pointer dereference while processing XPath XML expressions. An attacker can cause a crash and disrupt service availability by sending specially crafted input that triggers the dereference.

Remediation

Upgrade nokogiri to version 1.18.9 or higher.

References

• Fix Commit
• Red Hat Bugzilla Bug

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Out-of-bounds Read due to improper namespace processing of sch:name elements in xmlSchematronFormatReport() function. An attacker can cause a denial of service or potentially execute arbitrary code by providing specially crafted XML input.

Remediation

Upgrade nokogiri to version 1.18.9 or higher.

References

• Fix Commit
• Red Hat Bugzilla Bug

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Stack-based Buffer Overflow via the xmlBuildQName function. An attacker can cause a crash and denial of service by supplying specially crafted XML input that triggers an integer overflow and subsequent stack buffer overflow.

Remediation

Upgrade nokogiri to version 1.18.9 or higher.

References

• Fix Commit
• Red Hat Bugzilla Bug
• Release Notes

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling in the Rack::QueryParser. An attacker can exhaust memory and CPU by sending HTTP requests containing an excessively large number of &-separated query parameters.

Workaround

This vulnerability can be avoided by any means that limits the length of incoming raw strings or application/x-www-form-urlencoded data, including application-level limitation or employing middleware.

Remediation

Upgrade rack to version 2.2.14, 3.0.16, 3.1.14 or higher.

References

• GitHub Commit
• GitHub Commit
• GitHub Commit

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the Rack::Multipart::Parser. An attacker can exhaust system memory and cause process termination or severe slowdown by sending multipart requests with headers that never terminate, leading to unbounded memory allocation.

Workaround

This vulnerability can be mitigated by restricting maximum request sizes at the proxy or web server layer, such as configuring Nginx with client_max_body_size.

Remediation

Upgrade rack to version 2.2.19, 3.1.17, 3.2.2 or higher.

References

• GitHub Commit
• GitHub Commit
• GitHub Commit

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the Rack::Multipart::Parser. An attacker can exhaust system memory by sending multipart form submissions with excessively large non-file fields, leading to process crashes or degraded performance due to memory exhaustion and increased garbage collection overhead.

Workaround

This vulnerability can be mitigated by restricting the maximum request body size at the web-server or proxy layer (such as configuring Nginx client_max_body_size) and by validating and rejecting unusually large form fields at the application level.

Remediation

Upgrade rack to version 2.2.19, 3.1.17, 3.2.2 or higher.

References

• GitHub Commit
• GitHub Commit
• GitHub Commit

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the Rack::Multipart::Parser. An attacker can cause excessive memory consumption and potential process termination by sending multipart/form-data requests with a large preamble, leading to significant memory spikes and possible denial of service. The impact increases with higher allowed request sizes and concurrency.

Workaround

This vulnerability can be mitigated by limiting the total request body size at the proxy or web server level and by monitoring memory usage and setting per-process memory limits to prevent out-of-memory conditions.

Remediation

Upgrade rack to version 2.2.19, 3.1.17, 3.2.2 or higher.

References

• GitHub Commit
• GitHub Commit
• GitHub Commit

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the Rack::Request#POST process. An attacker can exhaust system memory by sending large application/x-www-form-urlencoded request bodies, causing application slowdowns or termination by the operating system due to out-of-memory conditions. This occurs before any parameter parsing or configured parsing limits are enforced, allowing unbounded memory allocation proportional to the request size and concurrency.

Workaround

This vulnerability can be mitigated by enforcing strict maximum body size at the proxy or web server layer, such as configuring Nginx client_max_body_size or Apache LimitRequestBody.

Remediation

Upgrade rack to version 3.2.3, 3.1.18, 2.2.20 or higher.

References

• GitHub Commit
• GitHub Commit
• GitHub Commit

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Relative Path Traversal in the can_serve() function in Rack::Static that enables local file inclusion. An attacker who knows the exact path to any file in the root: file directory can access it by supplying a path traversing pathname.

Remediation

Upgrade rack to version 2.2.13, 3.0.14, 3.1.12 or higher.

References

• GitHub Commit
• GitHub Commit

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Improper Handling of Unexpected Data Type due to incorrectly checking the types of arguments to various constructors in HTML4::SAX and XML::SAX, which causes a segmentation fault.

Remediation

Upgrade nokogiri to version 1.13.6 or higher.

References

• GitHub Commit
• GitHub PR
• RedHat Bugzilla Bug

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling due to params_limit only being enforced for parameters separated by &, while still splitting on both & and ; in the QueryParser. An attacker can exhaust system resources and cause service disruption by submitting a large number of parameters separated by semicolons, bypassing the intended parameter count limit.

Note:

This is only exploitable if the QueryParser is used directly with its default configuration (no explicit delimiter).

Workaround

This vulnerability can be mitigated by configuring QueryParser with an explicit delimiter (such as &) or by enforcing query string and request size limits at the web server or proxy layer to mitigate excessive parsing overhead.

Remediation

Upgrade rack to version 2.2.18 or higher.

References

• GitHub Commit

Overview

rubyzip is a ruby module for reading and writing zip files.

Affected versions of this package are vulnerable to Denial of Service (DoS). It is possible for a crafted ZIP file to bypass application checks on ZIP entry sizes because data about the uncompressed size can be spoofed. This allows attackers to cause a denial of service through maximum disk consumption. By default, the validate_entry_sizes option should be set to true, so that callers can trust an entry's reported size when using extract.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade rubyzip to version 1.3.0 or higher.

References

• GitHub PR

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Command Injection via the undocumented method Nokogiri::CSS::Tokenizer#load_file. This allows commands to be executed in a subprocess.

Remediation

Upgrade nokogiri to version 1.10.4 or higher.

References

• GitHub Commit
• GitHub Commit
• GitHub Issue
• HackerOne Report (Private)

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Use After Free via the ID and IDREF attributes, when using the xmlReader interface with validation or when a document is parsed with XML_PARSE_DTDVALID and without XML_PARSE_NOENT. This can lead to the value of ID attributes to not be normalized after potentially expanding entities in xmlRemoveID, which will cause later calls to xmlGetID to return a pointer to previously freed memory.

Remediation

Upgrade nokogiri to version 1.13.2 or higher.

References

• Gitlab Commit
• Nikigiri GHSA
• RedHat Bugzilla Bug

Overview

ffi is a ruby extension for programmatically loading dynamic libraries, binding functions within them, and calling those functions from Ruby code.

Affected versions of this package are vulnerable to DLL Loading Issue on Windows OS, when a Symbol is used as DLL name instead of a String.

Remediation

Upgrade ffi to version 1.9.24 or higher.

References

• GitHub Commit

Overview

addressable is an is an alternative implementation to the URI implementation that is part of Ruby's standard library.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) within the URI template implementation. A maliciously crafted template may result in uncontrolled resource consumption.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

• A The string must start with the letter 'A'
• (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
• D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

1. CCC
2. CC+C
3. C+CC
4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade addressable to version 2.8.0 or higher.

References

• GitHub Commit
• RedHat Bugzilla Bug

Overview

chef is a system integration framework, built to bring the benefits of configuration management to your entire infrastructure.

Affected versions of this package are vulnerable to Information Exposure. The knife bootstrap command in chef leaks the validator.pem private RSA key to /var/log/messages.

Remediation

Upgrade chef to version 15.4.22 or higher.

References

• GitHub Issue
• GitHub Issue
• GitHub PR
• NVD

Overview

minitar is a pure-Ruby library that provides the ability to deal with POSIX tar(1) archive files.

Affected versions of the package are vulnerable to Arbitrary File Write via Archive Extraction (AKA "Zip Slip").

It is exploited using a specially crafted zip archive, that holds path traversal filenames. When exploited, a filename in a malicious archive is concatenated to the target extraction directory, which results in the final path ending up outside of the target folder. For instance, a zip may hold a file with a "../../file.exe" location and thus break out of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicous file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

+2018-04-15 22:04:29 ..... 19 19 good.txt

+2018-04-15 22:04:42 ..... 20 20 ../../../../../../root/.ssh/authorized_keys

Related to rubyzip and archive-tar-minitar.

Remediation

Upgrade minitar to version 0.6 or higher.

References

• https://github.com/halostatue/minitar/commit/c31ad52ab502859392cf218eb1f947ac78d2a3fd
• https://github.com/halostatue/minitar/issues/16
• https://github.com/snyk/zip-slip-vulnerability
• https://security.snyk.io/research/zip-slip-vulnerability

Overview

mixlib-archive is a simple interface to various archive formats

Affected versions of this package are vulnerable to Directory Traversal allowing attackers to overwrite arbitrary files by supplying a filename for a tar archive involving ...

Details

A Directory Traversal attack (also known as path traversal) aims to access files and directories that are stored outside the intended folder. By manipulating files with "dot-dot-slash (../)" sequences and its variations, or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system, including application source code, configuration, and other critical system files.

Directory Traversal vulnerabilities can be generally divided into two types:

• Information Disclosure: Allows the attacker to gain information about the folder structure or read the contents of sensitive files on the system.

st is a module for serving static files on web pages, and contains a vulnerability of this type. In our example, we will serve files from the public route.

If an attacker requests the following URL from our server, it will in turn leak the sensitive private key of the root user.

curl http://localhost:8080/public/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/root/.ssh/id_rsa

Note %2e is the URL encoded version of . (dot).

• Writing arbitrary files: Allows the attacker to create or replace existing files. This type of vulnerability is also known as Zip-Slip.

One way to achieve this is by using a malicious zip archive that holds path traversal filenames. When each filename in the zip archive gets concatenated to the target extraction folder, without validation, the final path ends up outside of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicious file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

2018-04-15 22:04:29 .....           19           19  good.txt
2018-04-15 22:04:42 .....           20           20  ../../../../../../root/.ssh/authorized_keys

Remediation

Upgrade mixlib-archive to version 0.4.0 or higher.

References

• GitHub ChangeLog
• GitHub Commit
• GitHub PR

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Denial of Service (DoS). Vulnerable version of libxml2 was used.

The fix to this updates the vendored libxml2 from v2.9.10 to v2.9.12 which addresses:

• CVE-2019-20388
• CVE-2020-24977
• CVE-2021-3517
• CVE-2021-3518
• CVE-2021-3537
• CVE-2021-3541

Please note that this advisory only applies to the CRuby implementation of Nokogiri < 1.11.4, and only if the packaged version of libxml2 is being used. If you've overridden defaults at installation time to use system libraries instead of packaged libraries, you should instead pay attention to your distro's libxml2 release announcements.

NOTE: This vulnerability has also been identified as: CVE-2021-3537, CVE-2021-3541, CVE-2020-24977, CVE-2021-3517, CVE-2021-3518

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade nokogiri to version 1.11.4 or higher.

References

• GitHub Advisory
• GitHub PR
• POC: Potential Exploit

Overview

nokogiri is an HTML, XML, SAX, and Reader parser. Among Nokogiri's features is the ability to search documents via XPath or CSS3 selectors.

Affected versions of this package are vulnerable to Denial of Service (DoS), due to using vulnerable version of libxml2. When expanding a parameter entity in a DTD, an infinite recursion could occur and halt expected execution or lead to memory exhaustion.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade nokogiri to version 1.8.2 or higher.

References

• Git Hub Issue
• Bugzilla bug

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Denial of Service (DoS) via the xerces:xercesImpldependency, as its XML parser consumes excessive amount of resources when handling specially crafted XML document payloads due to an infinite loop.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade nokogiri to version 1.13.4 or higher.

References

• GitHub Release
• Google Groups Forum

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Denial of Service (DoS). It bundles the libxml2 library, which is vulnerable in versions below 2.9.10

##Details Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade nokogiri to version 1.10.8 or higher.

References

• GitHub Commit

• GitHub Security Advisory

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Denial of Service (DoS). Vulnerable version of libxml2 was used.

The fix to this updates the vendored libxml2 from v2.9.10 to v2.9.12 which addresses:

• CVE-2019-20388
• CVE-2020-24977
• CVE-2021-3517
• CVE-2021-3518
• CVE-2021-3537
• CVE-2021-3541

Please note that this advisory only applies to the CRuby implementation of Nokogiri < 1.11.4, and only if the packaged version of libxml2 is being used. If you've overridden defaults at installation time to use system libraries instead of packaged libraries, you should instead pay attention to your distro's libxml2 release announcements.

NOTE: This vulnerability has also been identified as: CVE-2021-3537, CVE-2021-3541, CVE-2019-20388, CVE-2021-3517, CVE-2021-3518

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade nokogiri to version 1.11.4 or higher.

References

• GitHub Advisory
• GitHub PR
• POC: Potential Exploit

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Denial of Service (DoS). Vulnerable version of libxml2 was used.

The fix to this updates the vendored libxml2 from v2.9.10 to v2.9.12 which addresses:

• CVE-2019-20388
• CVE-2020-24977
• CVE-2021-3517
• CVE-2021-3518
• CVE-2021-3537
• CVE-2021-3541

Please note that this advisory only applies to the CRuby implementation of Nokogiri < 1.11.4, and only if the packaged version of libxml2 is being used. If you've overridden defaults at installation time to use system libraries instead of packaged libraries, you should instead pay attention to your distro's libxml2 release announcements.

NOTE: This vulnerability has also been identified as: CVE-2021-3537, CVE-2021-3541, CVE-2019-20388, CVE-2020-24977, CVE-2021-3518

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade nokogiri to version 1.11.4 or higher.

References

• GitHub Advisory
• GitHub PR
• POC: Potential Exploit

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Denial of Service (DoS). Vulnerable version of libxml2 was used.

The fix to this updates the vendored libxml2 from v2.9.10 to v2.9.12 which addresses:

• CVE-2019-20388
• CVE-2020-24977
• CVE-2021-3517
• CVE-2021-3518
• CVE-2021-3537
• CVE-2021-3541

Please note that this advisory only applies to the CRuby implementation of Nokogiri < 1.11.4, and only if the packaged version of libxml2 is being used. If you've overridden defaults at installation time to use system libraries instead of packaged libraries, you should instead pay attention to your distro's libxml2 release announcements.

NOTE: This vulnerability has also been identified as: CVE-2021-3537, CVE-2021-3541, CVE-2019-20388, CVE-2020-24977, CVE-2021-3517

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade nokogiri to version 1.11.4 or higher.

References

• GitHub Advisory
• GitHub PR
• POC: Potential Exploit

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Denial of Service (DoS). Vulnerable version of libxml2 was used.

The fix to this updates the vendored libxml2 from v2.9.10 to v2.9.12 which addresses:

• CVE-2019-20388
• CVE-2020-24977
• CVE-2021-3517
• CVE-2021-3518
• CVE-2021-3537
• CVE-2021-3541

Please note that this advisory only applies to the CRuby implementation of Nokogiri < 1.11.4, and only if the packaged version of libxml2 is being used. If you've overridden defaults at installation time to use system libraries instead of packaged libraries, you should instead pay attention to your distro's libxml2 release announcements.

NOTE: This vulnerability has also been identified as: CVE-2021-3541, CVE-2019-20388, CVE-2020-24977, CVE-2021-3517, CVE-2021-3518

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade nokogiri to version 1.11.4 or higher.

References

• GitHub Advisory
• GitHub PR
• POC: Potential Exploit

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Denial of Service (DoS). Vulnerable version of libxml2 was used.

The fix to this updates the vendored libxml2 from v2.9.10 to v2.9.12 which addresses:

• CVE-2019-20388
• CVE-2020-24977
• CVE-2021-3517
• CVE-2021-3518
• CVE-2021-3537
• CVE-2021-3541

Please note that this advisory only applies to the CRuby implementation of Nokogiri < 1.11.4, and only if the packaged version of libxml2 is being used. If you've overridden defaults at installation time to use system libraries instead of packaged libraries, you should instead pay attention to your distro's libxml2 release announcements.

NOTE: This vulnerability has also been identified as: CVE-2021-3537, CVE-2019-20388, CVE-2020-24977, CVE-2021-3517, CVE-2021-3518

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade nokogiri to version 1.11.4 or higher.

References

• GitHub Advisory
• GitHub PR
• POC: Potential Exploit

Overview

nokogiri is an HTML, XML, SAX, and Reader parser. Among Nokogiri's features is the ability to search documents via XPath or CSS3 selectors.

Affected versions of this package are vulnerable to several Denial of Service (DoS) vulnerabilities. Nokogiri bundles the libxml2 library, which is vulnerable in versions through 2.9.6.

CVE-2018-14404

A NULL pointer dereference vulnerability exists in the xpath.c:xmlXPathCompOpEval() function of libxml2 through 2.9.8 when parsing an invalid XPath expression in the XPATH_OP_AND or XPATH_OP_OR case. Applications processing untrusted XSL format inputs with the use of the libxml2 library may be vulnerable to a denial of service attack due to a crash of the application

CVE-2018-14567

If --with-lzma is used, allows remote attackers to cause a denial of service (infinite loop) via a crafted XML file that triggers LZMA_MEMLIMIT_ERROR, as demonstrated by xmllint infinite loop in LZMA decompression.

Remediation

Upgrade nokogiri to version 1.8.5 or higher.

References

• https://github.com/sparklemotion/nokogiri/commit/7b8cd0f5b15a926e92c869b450dd6f71cdd17b61
• https://github.com/sparklemotion/nokogiri/issues/1785
• https://github.com/sparklemotion/nokogiri/pull/1786

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Heap-based Buffer Overflow through the xmlHTMLPrintFileContext function in xmllint.c. An attacker can read memory contents that may contain sensitive data by triggering a buffer over-read condition.

Remediation

Upgrade nokogiri to version 1.16.5 or higher.

References

• Gitlab Commit
• Gitlab Commit
• Gitlab Issue
• Gitlab Release
• Gitlab Release

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to NULL Pointer Dereference due to the usage of a vulnerable version of the bundled libxml2 package.

Remediation

Upgrade nokogiri to version 1.13.9 or higher.

References

• GitHub Commit
• GitHub Release

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Out-of-bounds Write via the zlib dependency which allows memory corruption when deflating if the input has many distant matches.

Remediation

Upgrade nokogiri to version 1.13.4 or higher.

References

• GitHub Release
• Google Groups Forum

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) due to an expression that is susceptible to excessive backtracking when attempting to detect encoding in HTML documents.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

• A The string must start with the letter 'A'
• (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
• D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

1. CCC
2. CC+C
3. C+CC
4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade nokogiri to version 1.13.4 or higher.

References

• GitHub Commit

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Use After Free in the xmlSchemaItemListAdd() function in xmlschemas.c, which is exploitable by supplying a malicious .xsd schema for validation. it may also be exploitable when an xsd:keyref is provided in combination with recursively defined types that have additional identity constraints, for validation against a non malicious schema.

Remediation

Upgrade nokogiri to version 1.18.3 or higher.

References

• GitHub Commit
• Gitlab Commit
• Gitlab Issue

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to XML External Entity (XXE) Injection. Users of Nokogiri on JRuby who parse untrusted documents using any of these classes are affected:

• Nokogiri::XML::SAX::Parse
• Nokogiri::HTML4::SAX::Parser or its alias Nokogiri::HTML::SAX::Parser
• Nokogiri::XML::SAX::PushParser
• Nokogiri::HTML4::SAX::PushParser or its alias Nokogiri::HTML::SAX::PushParser.

CRuby users are not affected.

Details

XXE Injection is a type of attack against an application that parses XML input. XML is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. By default, many XML processors allow specification of an external entity, a URI that is dereferenced and evaluated during XML processing. When an XML document is being parsed, the parser can make a request and include the content at the specified URI inside of the XML document.

Attacks can include disclosing local files, which may contain sensitive data such as passwords or private user data, using file: schemes or relative paths in the system identifier.

For example, below is a sample XML document, containing an XML element- username.

<xml>
<?xml version="1.0" encoding="ISO-8859-1"?>
   <username>John</username>
</xml>

An external XML entity - xxe, is defined using a system identifier and present within a DOCTYPE header. These entities can access local or remote content. For example the below code contains an external XML entity that would fetch the content of /etc/passwd and display it to the user rendered by username.

<xml>
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE foo [
   <!ENTITY xxe SYSTEM "file:///etc/passwd" >]>
   <username>&xxe;</username>
</xml>

Other XXE Injection attacks can access local resources that may not stop returning data, possibly impacting application availability and leading to Denial of Service.

Remediation

Upgrade nokogiri to version 1.12.5 or higher.

References

• GitHub Commit
• GitHub Release

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Denial of Service (DoS) via the multipart parsing component. Exploiting this vulnerability is possible when carefully crafted multipart POST requests cause Rack's multipart parser to take much longer than expected.

Notes:

Impacted code will use Rack's multipart parser to parse multipart posts. This includes directly using the multipart parser like this:

params = Rack::Multipart.parse_multipart(env)

It also includes reading POST data from a Rack request object like this:

p request.POST # read POST data 

p request.params # reads both query params and POST data

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade rack to version 2.0.9.1, 2.1.4.1, 2.2.3.1 or higher.

References

• GitHub Commit
• Google Groups Forum

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Denial of Service (DoS) via the Multipart MIME parsing functionality in parser.rb, which doesn't limit the number of total parts that can be uploaded. Exploiting this vulnerability is possible via a carefully crafted request, which might result in multipart parsing taking longer than expected.

Workaround

A proxy can be configured to limit the POST body size, which will mitigate this issue.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade rack to version 2.0.9.3, 2.1.4.3, 2.2.6.3, 3.0.4.2 or higher.

References

• GitHub Commit
• Security Advisory

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Denial of Service (DoS) in handling of the Range request header. Carefully crafted Range headers can cause a server to respond with an unexpectedly large response. This issue is present when the Rack::File middleware or the Rack::Utils.byte_ranges methods are used (which includes applications built with Rails).

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade rack to version 2.2.8.1, 3.0.9.1 or higher.

References

• GitHub Commit
• GitHub Release
• GitHub Release
• Vulnerability Advisory

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Directory Traversal. If certain directories exist in a directory that is managed by Rack::Directory, an attacker could, using this vulnerability, read the contents of files on the server that were outside of the root specified in the Rack::Directory initializer.

Details

A Directory Traversal attack (also known as path traversal) aims to access files and directories that are stored outside the intended folder. By manipulating files with "dot-dot-slash (../)" sequences and its variations, or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system, including application source code, configuration, and other critical system files.

Directory Traversal vulnerabilities can be generally divided into two types:

• Information Disclosure: Allows the attacker to gain information about the folder structure or read the contents of sensitive files on the system.

st is a module for serving static files on web pages, and contains a vulnerability of this type. In our example, we will serve files from the public route.

If an attacker requests the following URL from our server, it will in turn leak the sensitive private key of the root user.

curl http://localhost:8080/public/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/root/.ssh/id_rsa

Note %2e is the URL encoded version of . (dot).

• Writing arbitrary files: Allows the attacker to create or replace existing files. This type of vulnerability is also known as Zip-Slip.

One way to achieve this is by using a malicious zip archive that holds path traversal filenames. When each filename in the zip archive gets concatenated to the target extraction folder, without validation, the final path ends up outside of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicious file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

2018-04-15 22:04:29 .....           19           19  good.txt
2018-04-15 22:04:42 .....           20           20  ../../../../../../root/.ssh/authorized_keys

Remediation

Upgrade rack to version 2.1.3 or higher.

References

• Google Group Forum

Overview

yajl-ruby Ruby C bindings to the excellent Yajl JSON stream-based parser library.

Affected versions of this project are vulnerable to Denial of Service (DoS) attacks. When a crafted JSON file is supplied to Yajl::Parser.new.parse, the whole ruby process crashes with a SIGABRT in the yajl_string_decode function in yajl_encode.c. This results in the whole ruby process terminating and potentially a denial of service.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade yajl-ruby to version 1.3.1 or higher.

References

• GitHub Issue
• GitHub Commit

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to XML External Entity (XXE) Injection when opting into the DTDLOAD option and opting out of the NONET option. Nokogiri is affected by series of vulnerabilities in libxml2 and libxslt, which are libraries it depends on. When handling the expansion of XML external entities (XXE) in libxml2, you can specify documents to be read. Opting into the DTDLOAD option and opting out of the NONET option in Nokogiri allows unknown documents to be loaded from the network. This can be used by attackers to load specially crafted XML documents on an internal XML parsing service and may lead to unauthorized disclosure of potentially sensitive information.

Note: This vulnerability exists also in versions <1.5.4 regardless of the options opted into or out of. See more information here

Disclosure Timeline

• January 11th, 2017 - Reported the issue to Mike Dalessio of Nokogiri Core.
• January 11th, 2017 - Issue triaged and acknowledged by Mike Dalessio of Nokogiri Core.
• June 16th, 2018 - A fix has been introduced in Nokogiri 1.8.3 through libxml2 2.9.8.

Details

XXE Injection is a type of attack against an application that parses XML input. XML is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. By default, many XML processors allow specification of an external entity, a URI that is dereferenced and evaluated during XML processing. When an XML document is being parsed, the parser can make a request and include the content at the specified URI inside of the XML document.

Attacks can include disclosing local files, which may contain sensitive data such as passwords or private user data, using file: schemes or relative paths in the system identifier.

For example, below is a sample XML document, containing an XML element- username.

<xml>
<?xml version="1.0" encoding="ISO-8859-1"?>
   <username>John</username>
</xml>

An external XML entity - xxe, is defined using a system identifier and present within a DOCTYPE header. These entities can access local or remote content. For example the below code contains an external XML entity that would fetch the content of /etc/passwd and display it to the user rendered by username.

<xml>
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE foo [
   <!ENTITY xxe SYSTEM "file:///etc/passwd" >]>
   <username>&xxe;</username>
</xml>

Other XXE Injection attacks can access local resources that may not stop returning data, possibly impacting application availability and leading to Denial of Service.

Remediation

Upgrade nokogiri to version 1.8.3 or higher.

References

• CVE Details
• GitHub Issue

Overview

rake is a Make-like program implemented in Ruby.

Affected versions of this package are vulnerable to Arbitrary Code Injection in Rake::FileList when supplying a filename that begins with the pipe character |.

PoC by Katsuhiko Yoshida

% ls -1
Gemfile
Gemfile.lock
poc_rake.rb
vendor
| touch evil.txt
% bundle exec ruby poc_rake.rb
["poc_rake.rb", "Gemfile", "Gemfile.lock", "| touch evil.txt", "vendor"]
poc_rake.rb:6:list.egrep(/something/)
Error while processing 'vendor': Is a directory @ io_fillbuf - fd:7 vendor
% ls -1
Gemfile
Gemfile.lock
evil.txt
poc_rake.rb
vendor
| touch evil.txt

Remediation

Upgrade rake to version 12.3.3 or higher.

References

• HackerOne Report

Overview

rubyzip is a ruby module for reading and writing zip files.

Affected versions of the package are vulnerable to Arbitrary File Write via Archive Extraction (AKA "Zip Slip").

It is exploited using a specially crafted zip archive, that holds path traversal filenames. When exploited, a filename in a malicious archive is concatenated to the target extraction directory, which results in the final path ending up outside of the target folder. For instance, a zip may hold a file with a "../../file.exe" location and thus break out of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicous file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

+2018-04-15 22:04:29 ..... 19 19 good.txt

+2018-04-15 22:04:42 ..... 20 20 ../../../../../../root/.ssh/authorized_keys

NOTE This vulnerability is due to a partial fix in CVE-2017-5946

Remediation

Upgrade rubyzip to version 1.2.2 or higher.

References

• https://github.com/rubyzip/rubyzip/commit/d07b13a6cf0a413e010c48879aebd9576bfb5f68
• https://github.com/rubyzip/rubyzip/issues/369
• https://github.com/rubyzip/rubyzip/pull/371
• https://github.com/rubyzip/rubyzip/pull/376

Overview

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Improper Output Neutralization for Logs through the Rack::CommonLogger process. An attacker can manipulate log entries by crafting input that includes newline characters to insert fraudulent entries or obscure real activity.

Remediation

Upgrade rack to version 2.2.11, 3.0.12, 3.1.10 or higher.

References

• GitHub Commit

Overview

Affected versions of this package are vulnerable to OS Command Injection via the merge tool. An attacker can execute arbitrary commands by supplying crafted input that is improperly handled during the construction of commands.

Remediation

Upgrade thor to version 1.4.0 or higher.

References

• GitHub Commit
• GitHub PR

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Stack-based Buffer Overflow in the xmlSnprintfElements() function. An attacker can overwrite out-of-bounds stack memory with XML NCName data by supplying a malicious XML document or malicious DTD.

This vulnerability is similar to the previously reported and patched (CVE-2017-9047)[https://security.snyk.io/vuln/SNYK-UNMANAGED-LIBXML2-3004044].

Remediation

Upgrade nokogiri to version 1.18.3 or higher.

References

• GitHub Commit
• Gitlab Commit
• Gitlab Issue

GPL-3.0 license