CVE-2026-40176highCWE-20CWE-78

CVE-2026-40176: high-severity vulnerability in composer

Composer is vulnerable to Command Injection via Malicious Perforce Repository

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41Vexday Risk Score

No sign of exploitation. It has a public proof of concept.

ssvc Attendcvss 7.8epss 1.0%
from disclosure to weapon1 day
Published on NVDApr 15
1st PoC+1d
Composer is a dependency manager for PHP. Versions 1.0 through 2.2.26 and 2.3 through 2.9.5 contain a command injection vulnerability in the Perforce::generateP4Command() method, which constructs shell commands by interpolating user-supplied Perforce connection parameters (port, user, client) without proper escaping. An attacker can inject arbitrary commands through these values in a malicious composer.json declaring a Perforce VCS repository, leading to command execution in the context of the user running Composer, even if Perforce is not installed. VCS repositories are only loaded from the root composer.json or the composer config directory, so this cannot be exploited through composer.json files of packages installed as dependencies. Users are at risk if they run Composer commands on untrusted projects with attacker-supplied composer.json files. This issue has been fixed in Composer 2.2.27 (2.2 LTS) and 2.9.6 (mainline).
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Affected products
composer · composer
⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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