CVE-2026-40176
What it is
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).
At a glance
- Exploitability
- Can be exploited locally on the machine without logging in, but needs a user to act. High risk of data exposure, data tampering, service disruption.
- Exploit odds
- 1.0% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 1.0% in the next 30 days (EPSS).
- Severity: 7.8 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 1.0% · EPSS, next 30 days
- Weakness
- CWE-20 · Improper input validation
- Record status
- Modified
Affected
- Getcomposer Composer ≤ 2.2.26
- Getcomposer Composer ≤ 2.9.5
Attack profile CVSS 3.1 · 7.8
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-40176.md and follow it. Check whether this project is affected by CVE-2026-40176. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://github.com/composer/composer/releases/tag/2.2.27
- https://github.com/composer/composer/releases/tag/2.9.6
- https://github.com/composer/composer/security/advisories/GHSA-wg36-wvj6-r67p
References
- https://access.redhat.com/errata/RHSA-2026:8165
- https://access.redhat.com/security/cve/CVE-2026-40176
- https://bugzilla.redhat.com/show_bug.cgi?id=2458828
- https://github.com/FriendsOfPHP/security-advisories/blob/master/composer/composer/CVE-2026-40176.yaml
- https://github.com/composer/composer/releases/tag/2.2.27
- https://github.com/composer/composer/releases/tag/2.9.6
- https://github.com/composer/composer/security/advisories/GHSA-wg36-wvj6-r67p
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40176.json
- https://access.redhat.com/errata/RHSA-2026:8165
- https://access.redhat.com/security/cve/CVE-2026-40176
- https://bugzilla.redhat.com/show_bug.cgi?id=2458828
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40176.json