CVE-2026-40261
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.69%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- EPSS
- 1.69% probability · 76th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-20, CWE-78
- Affected
- getcomposer/composer
- Source
- security-advisories@github.com
References
- https://github.com/composer/composer/releases/tag/2.9.6Release Notes
- https://github.com/composer/composer/security/advisories/GHSA-gqw4-4w2p-838qVendor Advisory
- https://access.redhat.com/errata/RHSA-2026:8165
- https://access.redhat.com/security/cve/CVE-2026-40261
- https://bugzilla.redhat.com/show_bug.cgi?id=2458841
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40261.json
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.