CVE-2026-59944

What it is

Composer is a dependency Manager for the PHP language. From 1.0 until 2.2.30 and from 2.3.0 until 2.10.3, a malicious or compromised dependency can bypass the earlier CVE-2026-59946 binary-path hardening because Composer validates literal parent-directory segments only during dependency resolution, while the symlink and installed-metadata paths described by the advisory skip that validation. A package can ship an in-package binary symlink that resolves outside its installation directory, or attacker-influenced vendor/composer/installed.json metadata can provide an escaping binary path during a reinstall or regeneration of missing vendor/bin entries. The installed-metadata path is reachable only when the vendor directory was not populated by the same validated install run, such as when it is restored from an untrusted cache, copied from an earlier build stage, carried over from an older Composer run, or writable by a lower-trust build step. Composer can follow the path, change the external target's permissions to make it world-readable and executable, and create a runnable vendor/bin proxy to that external file. The issue does not directly read or transmit data and does not by itself provide remote code execution. This issue is fixed in versions 2.2.30 and 2.10.3.

At a glance

Exploitability

Can be exploited locally on the machine without logging in, but needs a user to act. High risk of data exposure.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-16 17:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-09-30 17:43 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.5% in the next 30 days (EPSS).
• Severity: 6.1 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-09-16 17:17 UTC

Last modified

2026-09-30 17:43 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-22 · Path traversal

Record status

Awaiting Analysis

Attack profile CVSS 3.1 · 6.1

Attack vector

Local

Complexity

Low

Privileges needed

None

User interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-59944.md and follow it. Check whether this project is affected by CVE-2026-59944. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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