CVE-2015-8371 Composer allows cache poisoning from other projects built on the same host

What is CVE-2015-8371?

CVE-2015-8371 is a high-severity vulnerability in n/a, published on 21 Sep 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

Composer before 2016-02-10 allows cache poisoning from other projects built on the same host. This results in attacker-controlled code entering a server-side build process. The issue occurs because of the way that dist packages are cached. The cache key is derived from the package name, the dist type, and certain other data from the package repository (which may simply be a commit hash, and thus can be found by an attacker). Versions through 1.0.0-alpha11 are affected, and 1.0.0 is unaffected.

Weakness: CWE-345

Which versions are affected by CVE-2015-8371?

2 open source packages ship an affected version, including composer/composer. It affects 1 product.

Products include Getcomposer Composer.

How do I fix CVE-2015-8371?

Upgrade composer/composer to 1.0.0 or later.

Is CVE-2015-8371 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2015-8371 exists.

Other vulnerabilities in n/a

• CVE-2026-40261 Composer has Command Injection via Malicious Perforce Reference High 8.8
• CVE-2024-24821 Code execution and possible privilege escalation via compromised InstalledVersions.php or installed.php in Composer High 8.8
• CVE-2021-41116 Command injection in composer on Windows High 8.2
• CVE-2026-40176 Composer is vulnerable to Command Injection via Malicious Perforce Repository High 7.8
• CVE-2025-67746 Composer vulnerable to ANSI sequence injection Low 1.3

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2015-8371, GHSA-725m-w832-q973.