CVE-2026-59946: Composer path traversal in package bin field

CVE-2026-59946 · Severity: medium · CVSS 6.1 · Published 2026-07-08

Composer is a popular dependency manager for the PHP programming language. A vulnerability in how it handles package installation allows a malicious dependency to change the file permissions of sensitive files on the host machine, such as SSH keys or configuration files. This could allow other local users on a shared system to read private data that was previously restricted.

Technologies: Composer (Packagist), composer/composer (Packagist). Vendors: Packagist.

Quick answers

Is CVE-2026-59946 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-59946 being exploited in the wild.
How severe is CVE-2026-59946?
Medium severity, with a CVSS score of 6.1, published 8 July 2026.
Which products and versions are affected?
Composer (Packagist) >= 1.0, < 2.2.29; >= 2.3.0, < 2.10.2, >= 1.0.0, < 2.2.29; >= 2.3.0, < 2.10.2; composer/composer (Packagist) ECOSYSTEM:introduced=2.3.0,fixed=2.10.2.
Is there a fix for CVE-2026-59946?
Yes. composer/composer (Packagist): upgrade to 2.10.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-59946 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2026-59946?
Check whether you run Composer (Packagist) or composer/composer (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • composer/composer (Packagist): upgrade to 2.10.2 or later
    composer require composer/composer:^2.10.2

Technical details

A path traversal vulnerability exists in Composer's handling of the 'bin' field within a package's composer.json file. When installing a package, Composer attempts to make specified binaries executable by applying a chmod operation. By using '..' path segments in the bin field, a malicious package can target files outside the package's installation directory. If the user running Composer has sufficient permissions, the target file's mode is changed to 0755 (world-readable and world-executable). This can be triggered by any direct or transitive dependency during 'install', 'update', or 'require' operations. The issue is fixed in versions 2.2.29 and 2.10.2 by rejecting bin entries containing path traversal segments.

Affected products

  • Composer Composer >= 1.0.0, < 2.2.29; >= 2.3.0, < 2.10.2

Identifiers

  • CVE-2026-59946
  • GHSA-gjfg-22fp-rrxx

Timeline

  • 2026-07-01: disclosed
  • 2026-07-08: advisory: NVD publication
  • 2026-07-20: patched: GitHub Advisory updated with full details

References

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