CVE-2026-40176 HIGH

CVE-2026-40176: Composer is vulnerable to Command Injection via Malicious Perforce Repository

Vendor Composer
Product composer
Weakness CWE-20 · Input validation
Published April 15, 2026
Last update June 30, 2026

CVSS base score

7.8/10
Attack vector Local
Attack complexity Low
Privileges required None
User interaction Required
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

What the vulnerability does

01Description

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).

Key dates

02Disclosure timeline

April 15, 2026 CVE published
June 30, 2026 Record updated