Command Injection Vulnerability in Composer Dependency Manager by PHP
CVE-2026-40176

7.8HIGH

Key Information:

Vendor: Composer
Status: Composer
Vendor: CVE Published:; 15 April 2026

Badges

📈 Trended📈 Score: 1,880📰 News Worthy

What is CVE-2026-40176?

CVE-2026-40176 is a command injection vulnerability found in the Composer Dependency Manager, which is widely used in PHP development to manage libraries and dependencies. This vulnerability arises from the Perforce::generateP4Command() method, which constructs shell commands through the interpolation of user-supplied parameters without proper input validation or escaping. Attackers can exploit this flaw by injecting arbitrary shell commands into the values related to Perforce connection parameters—specifically port, user, and client—in a malicious composer.json file, leading to command execution in the context of the user running Composer. This is particularly dangerous as it can occur even if Perforce itself is not installed on the system. Organizations that execute Composer commands using untrusted or attacker-supplied composer.json files are at risk of compromising their systems.

Potential Impact of CVE-2026-40176

Arbitrary Command Execution: The most significant risk associated with this vulnerability is the potential for attackers to execute arbitrary commands on the host system. If successful, this can lead to unauthorized access and control over the affected environment, enabling further exploitation.
Escalation of Privileges: The command execution occurs in the context of the user running Composer, which can lead to privilege escalation. An attacker gaining this level of access could perform actions that compromise sensitive data or system integrity.
Compromise of Supply Chain Security: Given that Composer is a dependency manager, a successful exploitation of this vulnerability can affect the entire software supply chain. Malicious code could be injected into projects that are built with Composer, thereby impacting not just the immediate victim but potentially all projects dependent on the compromised libraries.

Affected Version(s)

composer >= 2.3, < 2.9.6 < 2.3, 2.9.6

composer >= 1.0, < 2.2.27 < 1.0, 2.2.27

News Articles

Laravel News

CVE-2026-40261 CVE-2026-40176

Composer 2.9.6 Fixes Two Perforce Command Injection Vulnerabilities - Laravel News

Composer 2.9.6 and 2.2.27 LTS fix two Perforce VCS driver command injection vulnerabilities that could lead to arbitrary command execution. Update immediately.