Command Injection Affecting composer/composer package, versions >=2.0.0, <2.2.27>=2.3.0, <2.9.6
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PHP-COMPOSERCOMPOSER-16066747
- published15 Apr 2026
- disclosed14 Apr 2026
- creditkodareef5
Introduced: 14 Apr 2026
NewCVE-2026-40261 (opens in a new tab)How to fix?
Upgrade composer/composer to version 2.2.27, 2.9.6 or higher.
Overview
composer/composer is a Dependency Manager for PHP. Composer helps you declare, manage and install dependencies of PHP projects. It ensures you have the right stack everywhere.
Affected versions of this package are vulnerable to Command Injection via the Perforce::syncCodeBase and Perforce::generateP4Command methods, which append user-controlled input from package metadata directly to shell commands without proper escaping. An attacker can execute arbitrary system commands by supplying crafted source references or URLs containing shell metacharacters in a malicious Composer repository. This is only exploitable if dependencies are installed or updated from source (such as with the --prefer-source flag or when installing dev-prefixed versions).
Workaround
This vulnerability can be mitigated by avoiding installation of dependencies from source by using the --prefer-dist flag or setting preferred-install: dist in configuration, and by only using trusted Composer repositories.