CVE-2026-59948
HighCVSS 7.0Exploitation Probability (EPSS)
Low risk3th percentile - higher than 3% of all known CVEs
Summary
A vulnerability in the Composer dependency manager for PHP allows an attacker to write files outside the vendor directory and project during package installation or update. The issue occurs when a package from an untrusted repository (other than Packagist.org or Private Packagist) uses an invalid name that is not properly validated before dependency-resolution results are written.
Risk Assessment
An attacker can overwrite critical system or project files, potentially leading to remote code execution, privilege escalation, or permanent environment damage.
Recommendation
Upgrade Composer to version 2.2.29 or 2.10.2 immediately (depending on the branch in use) and avoid using untrusted package repositories.
Other vulnerabilities in Composer
See all- CVE-2026-45793High
A vulnerability in Composer, a dependency manager for PHP, allows disclosure of GitHub OAuth tokens in error logs. Token validation using a regex rejects GITHUB_TOKEN values containing '-', and the rejected token is interpolated into an exception message, leading to leakage to stderr or CI logs.
- CVE-2026-59947Medium
Composer, a dependency manager for PHP, prior to versions 2.2.29 and 2.10.2 leaked credentials (e.g., GitHub tokens) to debug output when run with -vvv verbosity. The issue was due to missing sanitization of username-only URL credentials.
- CVE-2026-59946Medium
A vulnerability in the Composer dependency manager for PHP allows changing permissions of an existing host file to world-readable and world-executable. The issue occurs during package install, update, or require when a package bin entry contains '..' path segments.
- CVE-2026-40261High
Composer versions 1.0 through 2.2.26 and 2.3 through 2.9.5 contain a command injection vulnerability in the Perforce::syncCodeBase() and Perforce::generateP4Command() methods. An attacker can inject arbitrary commands through crafted source reference or source url values containing shell metacharacters, even if Perforce is not installed.
- CVE-2026-40176High
Command injection vulnerability in the Perforce::generateP4Command() method in Composer, a dependency manager for PHP. An attacker can inject arbitrary commands through Perforce connection parameters (port, user, client) in a malicious composer.json, leading to command execution in the context of the user running Composer.
Original NVD description (English source)
Composer is a dependency Manager for the PHP language. Prior to 2.2.29 and 2.10.2, a maliciously crafted package from an untrusted repository other than Packagist.org or Private Packagist can cause Composer to write attacker-controlled files outside the vendor directory and outside the project during install or update by using an invalid package name that is not correctly validated before dependency-resolution results are written or installed. This issue is fixed in versions 2.2.29 and 2.10.2.