CVE-2026-40261
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::syncCodeBase() method, which appends the $sourceReference parameter to a shell command without proper escaping, and additionally in the Perforce::generateP4Command() method as in GHSA-wg36-wvj6-r67p / CVE-2026-40176, which interpolates user-supplied Perforce connection parameters (port, user, client) from the source url field without proper escaping. An attacker can inject arbitrary commands through crafted source reference or source url values containing shell metacharacters, even if Perforce is not installed. Unlike CVE-2026-40176, the source reference and url are provided as part of package metadata, meaning any compromised or malicious Composer repository can serve package metadata declaring perforce as a source type with malicious values. This vulnerability is exploitable when installing or updating dependencies from source, including the default behavior when installing dev-prefixed versions. This issue has been fixed in Composer 2.2.27 (2.2 LTS) and 2.9.6 (mainline). If developers are unable to immediately update, they can avoid installing dependencies from source by using --prefer-dist or the preferred-install: dist config setting, and only use trusted Composer repositories as a workaround.
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-2026-40261
- https://www.suse.com/security/cve/CVE-2026-40261.html
- https://github.com/composer/composer/security/advisories/GHSA-gqw4-4w2p-838q
- https://nvd.nist.gov/vuln/detail/CVE-2026-40261
- https://github.com/FriendsOfPHP/security-advisories/blob/master/composer/composer/CVE-2026-40261.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.