Denial of Service (DoS)

Affecting nokogiri gem, versions <1.11.4

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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.

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

CVSS Score

7.5
high severity
  • Attack Vector
    Network
  • Attack Complexity
    Low
  • Privileges Required
    None
  • User Interaction
    None
  • Scope
    Unchanged
  • Confidentiality
    None
  • Integrity
    None
  • Availability
    High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Credit
Unknown
CVE
CVE-2019-20388 CVE-2020-24977 CVE-2021-3517 CVE-2021-3518 CVE-2021-3537 CVE-2021-3541
CWE
CWE-400
Snyk ID
SNYK-RUBY-NOKOGIRI-1293239
Disclosed
17 May, 2021
Published
18 May, 2021