CVE-2026-59946 Composer: Path traversal in package bin field lets dependencies chmod arbitrary host files
A malicious Composer package can use path traversal in its bin field to chmod arbitrary host files, potentially leading to privilege escalation or data modification.
- 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-2026-59946?
CVE-2026-59946 is a medium-severity path traversal vulnerability in composer, published on 8 Jul 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. Prior to 2.2.29 and 2.10.2, a Composer package bin entry containing .. path segments can resolve outside the package install directory and cause Composer's binary installation flow to chmod an existing host file to a world-readable and world-executable mode during composer install, update, or require. This issue is fixed in versions 2.2.29 and 2.10.2.
Which versions are affected by CVE-2026-59946?
5 open source packages ship an affected version, including composer/composer and composer.
| Package | Affected | Fixed in |
|---|---|---|
composer/composer Packagist | From 1.0.0 | 2.2.29 |
composer/composer Packagist | From 1.0.0 | 2.2.29 |
composer/composer Packagist | From 2.3.0 | 2.10.2 |
composer/composer Packagist | From 2.3.0 | 2.10.2 |
composer Bitnami | From 1.0.0 | 2.2.29, 2.10.2 |
Linux distribution packages (1)
composer Red Hat:hummingbird:1 | All versions | 0:2.10.2-1.hum1 |
How do I fix CVE-2026-59946?
Upgrade composer/composer to a fixed version for your release line: 2.2.29 or 2.10.2.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-59946 being exploited?
There is no known exploitation of CVE-2026-59946 in the wild and no public exploit code.
Sources
Also known as BIT-composer-2026-59946, CLEANSTART-2026-XS00515, DEBIAN-CVE-2026-59946, GHSA-gjfg-22fp-rrxx, MINI-2x76-2c3f-vphj, MINI-xvgc-rq86-jjv9 and 2 more.