CVE-2026-59944 Composer: CVE-2026-59946 fix bypass via symlinked package bin path
A malicious package can bypass binary path hardening via symlinks or metadata, allowing execution of external files with modified permissions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-59944?
CVE-2026-59944 is a medium-severity path traversal vulnerability in composer, published on 16 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Composer is a dependency Manager for the PHP language. From 1.0 until 2.2.30 and from 2.3.0 until 2.10.3, a malicious or compromised dependency can bypass the earlier CVE-2026-59946 binary-path hardening because Composer validates literal parent-directory segments only during dependency resolution, while the symlink and installed-metadata paths described by the advisory skip that validation. A package can ship an in-package binary symlink that resolves outside its installation directory, or attacker-influenced vendor/composer/installed.json metadata can provide an escaping binary path during a reinstall or regeneration of missing vendor/bin entries. The installed-metadata path is reachable only when the vendor directory was not populated by the same validated install run, such as when it is restored from an untrusted cache, copied from an earlier build stage, carried over from an older Composer run, or writable by a lower-trust build step. Composer can follow the path, change the external target's permissions to make it world-readable and executable, and create a runnable vendor/bin proxy to that external file. The issue does not directly read or transmit data and does not by itself provide remote code execution. This issue is fixed in versions 2.2.30 and 2.10.3.
Which versions are affected by CVE-2026-59944?
5 open source packages ship an affected version, including composer/composer and composer.
| Package | Affected | Fixed in |
|---|---|---|
composer/composer Packagist | From 1.0 | 2.2.30 |
composer/composer Packagist | From 1.0 | 2.2.30 |
composer/composer Packagist | From 2.3.0 | 2.10.3 |
composer/composer Packagist | From 2.3.0 | 2.10.3 |
composer Bitnami | From 1.0.0 | 2.2.30, 2.10.3 |
Linux distribution packages (1)
php-composer2 openSUSE:Tumbleweed | All versions | 2.10.3-1.1 |
How do I fix CVE-2026-59944?
Upgrade composer/composer to a fixed version for your release line: 2.2.30 or 2.10.3.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-59944 being exploited?
There is no known exploitation of CVE-2026-59944 in the wild and no public exploit code.
Sources
Also known as BIT-composer-2026-59944, DEBIAN-CVE-2026-59944, GHSA-96h3-5x6v-m776, MINI-482r-fqp5-8wh3, MINI-w5pg-ffpr-8px2, UBUNTU-CVE-2026-59944 and 1 more.