CVE-2026-40176
Description
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).
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Debian Mixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 2.8.8-1+deb13u2 |
| sid | Fixed | 2.9.7-1 |
| forky | Fixed | 2.9.7-1 |
| bullseye | Affected | — |
| bookworm | Fixed | 2.5.5-1+deb12u4 |
Package impact
| Ecosystem | Package | Vulnerable | Fixed |
|---|---|---|---|
| Packagist | composer/composer | >=2.3.0,<2.9.6 | 2.9.6 |
| Packagist | composer/composer | >=1.0.0,<2.2.27 | 2.2.27 |
References
- https://security-tracker.debian.org/tracker/CVE-2026-40176
- https://www.suse.com/security/cve/CVE-2026-40176.html
- https://github.com/composer/composer/security/advisories/GHSA-wg36-wvj6-r67p
- https://nvd.nist.gov/vuln/detail/CVE-2026-40176
- https://github.com/FriendsOfPHP/security-advisories/blob/master/composer/composer/CVE-2026-40176.yaml
- https://github.com/composer/composer
- https://github.com/composer/composer/releases/tag/2.9.6
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.