CVE-2026-84361: composer OS Command Injection

Vulnerability summary

CVE-2026-84361 is a high (CVSS 7.7) OS Command Injection vulnerability in composer. EPSS estimates a 0.55% chance of exploitation in the next 30 days, higher than 44.7% of scored vulnerabilities.

Timeline

1. 01-09-2026
   PublishedVulnerability first disclosed.
2. 03-09-2026
   Last modifiedVulnerability information updated.

Description

Composer is a dependency Manager for the PHP language. From 1.0 until 2.2.30 and 2.10.3, a malicious dependency package from a custom Composer repository or an untrusted composer.lock file could set source.type to perforce and source.url to an rsh: or jsh: P4PORT value. When the Perforce p4 client was installed and Composer installed the package from source through composer install or composer update, including --prefer-source, Composer\Util\Perforce passed the address to p4 without validation, causing p4 to run a local command with the privileges of the user or CI account. Packagist.org does not permit Perforce source metadata. This issue is fixed in versions 2.2.30 and 2.10.3.

• CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.