GHSA-gqw4-4w2p-838q · Severity: high · Ecosystem: composer — Composer has a command injection via malicious perforce reference
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.
Conclusion & alert: CVE-2026-40261 is rated Moderate Risk (40.7/100): CVSS High severity, with low exploitation likelihood (EPSS 0.05%). Mandatory action: Review affected assets and schedule remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-05-22 | 0.04% | 0.05% | +0.01% |
| 2 | 2026-04-16 | — | 0.04% | — |
Full EPSS history (2 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 8.8 | 3.1 | HIGH |
|
2.8 | 5.9 | [email protected] |
GHSA-gqw4-4w2p-838q · Severity: high · Ecosystem: composer — Composer has a command injection via malicious perforce reference
| vendor | priority | summary | link |
|---|---|---|---|
alpine
|
— | CVE-2026-40261: 1 source package rows (composer); 2 state rows across 2 repos (3.23-community, edge-community); fixed 2, open 0. | https://security.alpinelinux.org/vuln/CVE-2026-40261 |
debian
|
not yet assigned | CVE-2026-40261 not yet assigned priority: Debian including 1 source packages (composer), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. | https://security-tracker.debian.org/tracker/CVE-2026-40261 |
redhat
|
high | — | https://access.redhat.com/security/cve/CVE-2026-40261 |
suse
|
high | — | https://www.suse.com/security/cve/CVE-2026-40261/ |
ubuntu
|
medium | CVE-2026-40261 medium priority: Ubuntu including 1 source packages (composer), 8 status rows across 8 suites (bionic, focal, jammy, noble, questing, resolute, upstream, xenial): needs-triage 7, released 1. | https://ubuntu.com/security/CVE-2026-40261 |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| getcomposer | composer | >= 1.0.0, <= 2.2.26 | cpe:2.3:a:getcomposer:composer:*:*:*:*:*:*:*:* |
| getcomposer | composer | >= 2.3.0, <= 2.9.5 | cpe:2.3:a:getcomposer:composer:*:*:*:*:*:*:*:* |
| URL | Tags |
|---|---|
| https://github.com/composer/composer/releases/tag/2.9.6 | Release Notes |
| https://github.com/composer/composer/security/advisories/GHSA-gqw4-4w2p-838q | Vendor Advisory |