GHSA-wg36-wvj6-r67p: composer/composer (CVE-2026-40176)

Package	Ecosystem	Affected	Fixed in
composer/composer	Packagist	>=2.3.0, <2.9.6 \|\| >=1.0.0, <2.2.27	2.9.6, 2.2.27

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Composer versions from 1.0.0 before 2.2.27, and from 2.3.0 before 2.9.6, are vulnerable to command injection through the Perforce connection parameters (port, user, client) in a VCS repository entry. An attacker who supplies a malicious composer.json in the project being run, or in the global Composer config directory, can execute arbitrary commands as the user running Composer, even without Perforce installed. Upgrade to Composer 2.2.27 or 2.9.6. Until then, only run Composer on trusted projects and inspect Perforce-related fields in composer.json first.

Written 14 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
7.8	High	3.1	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.011, the 65th percentile, on 15 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

14 Apr 2026, 09:46 UTC Published by the maintainers as a GitHub repository advisory
14 Apr 2026, 20:03 UTC Confirmed by GitHub Advisory Database
15 Apr 2026, 20:47 UTC Confirmed by the CVE List
15 Apr 2026, 21:17 UTC Confirmed by NVD
31 Oct 2026, 14:02 UTC First seen by agentprime
31 Oct 2026, 14:02 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.