OS Command Injection in composer - CVE-2026-40261
Published: April 14, 2026
Vulnerability identifier: #VU125894
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2026-40261
CWE-ID: CWE-78
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: getcomposer.org
Affected software:
composer
composer
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary commands.
The vulnerability exists due to command injection in the Perforce::syncCodeBase() and Perforce::generateP4Command() methods when processing package metadata containing a crafted Perforce source reference or source url. A remote attacker can supply a malicious package through a Composer repository to execute arbitrary commands.
The issue is exploitable when installing or updating dependencies from source, including with --prefer-source and by default for dev prefixed versions. User interaction is required to install or update the dependency.
How to mitigate CVE-2026-40261
Install security update from vendor's website.