New PHP Composer Flaws Enable Arbitrary Command Execution — Patches Released

Summary

Two command injection vulnerabilities (CVE-2026-40176, CVSS 7.8 and CVE-2026-40261, CVSS 8.8) were disclosed in Composer, a PHP package manager, affecting versions 2.3–2.9.6 and 2.0–2.2.27. The flaws stem from improper input validation in the Perforce VCS driver, allowing attackers to inject arbitrary commands through malicious composer.json files or crafted source references. Patches have been released (versions 2.9.6 and 2.2.27), and Packagist.org has disabled Perforce metadata publication as a precaution; no active exploitation in the wild has been detected.

Full text

New PHP Composer Flaws Enable Arbitrary Command Execution — Patches Released Ravie LakshmananApr 14, 2026Vulnerability / DevSecOps Two high-severity security vulnerabilities have been disclosed in Composer, a package manager for PHP, that, if successfully exploited, could result in arbitrary command execution. The vulnerabilities have been described as command injection flaws affecting the Perforce VCS (version control software) driver. Details of the two flaws are below - CVE-2026-40176 (CVSS score: 7.8) - An improper input validation vulnerability that could allow an attacker controlling a repository configuration in a malicious composer.json declaring a Perforce VCS repository to inject arbitrary commands, resulting in command execution in the context of the user running Composer. CVE-2026-40261 (CVSS score: 8.8) - An improper input validation vulnerability stemming from inadequate escaping that could allow an attacker to inject arbitrary commands through a crafted source reference containing shell metacharacters. In both cases, Composer would execute these injected commands even if Perforce VCS is not installed, the maintainers noted in an advisory. The vulnerabilities affect the following versions - >= 2.3, < 2.9.6 (Fixed in version 2.9.6) >= 2.0, < 2.2.27 (Fixed in version 2.2.27) If immediate patching is not an option, it's advised to inspect composer.json files before running Composer and verify that Perforce-related fields contain valid values. It's also recommended to only use trusted Composer repositories, run Composer commands on projects from trusted sources, and avoid installing dependencies using the "--prefer-dist" or the "preferred-install: dist" configuration setting. Composer said it scanned Packagist.org and did not find any evidence of the aforementioned vulnerabilities being exploited by threat actors by publishing packages with malicious Perforce information. A new release is expected to be shipped for Private Packagist Self-Hosted customers. "As a precaution, publication of Perforce source metadata has been disabled on Packagist.org since Friday, April 10th, 2026," it said. "Composer installations should be updated immediately regardless." Found this article interesting? Follow us on Google News, Twitter and LinkedIn to read more exclusive content we post. SHARE     Tweet Share Share Share SHARE  Command Injection, Composer, cybersecurity, DevSecOps, Open Source, Perforce, PHP, Software Supply Chain, Vulnerability Trending News Microsoft Warns of WhatsApp-Delivered VBS Malware Hijacking Windows via UAC Bypass New Chrome Zero-Day CVE-2026-5281 Under Active Exploitation — Patch Released Apple Expands iOS 18.7.7 Update to More Devices to Block DarkSword Exploit Hackers Exploit CVE-2025-55182 to Breach 766 Next.js Hosts, Steal Credentials New SparkCat Variant in iOS, Android Apps Steals Crypto Wallet Recovery Phrase Images Microsoft Details Cookie-Controlled PHP Web Shells Persisting via Cron on Linux Servers Fortinet Patches Actively Exploited CVE-2026-35616 in FortiClient EMS Block the Prompt, Not the Work: The End of "Doctor No" BKA Identifies REvil Leaders Behind 130 German Ransomware Attacks ⚡ Weekly Recap: Axios Hack, Chrome 0-Day, Fortinet Exploits, Paragon Spyware and More China-Linked Storm-1175 Exploits Zero-Days to Rapidly Deploy Medusa Ransomware New GPUBreach Attack Enables Full CPU Privilege Escalation via GDDR6 Bit-Flips Docker CVE-2026-34040 Lets Attackers Bypass Authorization and Gain Host Access Anthropic's Claude Mythos Finds Thousands of Zero-Day Flaws Across Major Systems AI Will Change Cybersecurity. Humans Will Define Its Success. A Lesson No Algorithm Can Teach The AI Arms Race – Why Unified Exposure Management Is Becoming a Boardroom Priority Popular Resources Learn How to Block Breached Passwords in Active Directory Before Attacks Get Full Visibility into Vendor and Internal Risk in One Platform [Guide] Get Practical Steps to Govern AI Agents with Runtime Controls Secure Your AI Systems Across the Full Lifecycle of Risks

Indicators of Compromise

• cve — CVE-2026-40176
• cve — CVE-2026-40261

Entities