Command Injection Flaw in Composer Affects PHP Dependency Management
CVE-2026-40261

8.8HIGH

Key Information:

Vendor

Composer

Status
Composer
Vendor
CVE Published:
15 April 2026

What is CVE-2026-40261?

A command injection vulnerability exists in Composer, a widely used PHP dependency manager, specifically in the Perforce::syncCodeBase() and Perforce::generateP4Command() methods. This flaw arises from the improper handling of the $sourceReference parameter and user-supplied Perforce connection parameters, allowing attackers to inject malicious commands via crafted values. A compromised Composer repository can serve package metadata that includes these unsafe parameters, rendering systems vulnerable during dependency installation or updates. To mitigate risks, users should upgrade to Composer versions 2.2.27 or 2.9.6 and employ safer installation practices by avoiding source installations.

Affected Version(s)

composer >= 2.3.0, < 2.9.6 < 2.3.0, 2.9.6

composer >= 1.0.0, < 2.2.27 < 1.0.0, 2.2.27

References

https://github.com/composer/composer/security/advisories/...
x_refsource_CONFIRM
https://github.com/composer/composer/releases/tag/2.9.6
x_refsource_MISC

CVSS V3.1

Score:
8.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.