Composer: Arbitrary file write outside vendor via malicious transitive package nameGHSA-499r-g7pc-vmp9
HIGHFix: composer/composer@502c6c4GHSA-499r-g7pc-vmp9 is a high-severity (CVSS 7) Path Traversal vulnerability in composer/composer. A fix is available for composer/composer — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-499r-g7pc-vmp9.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-499r-g7pc-vmp9 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 384,189 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
composer/composer🐘composer/composerReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
A maliciously crafted package, published on an untrusted third party repository other than Packagist.org or Private Packagist, can cause Composer to write files outside the vendor/ directory and outside your project, with attacker-controlled content, during a normal install or update through using an invalid package name, which was not correctly validated by Composer.
This is an arbitrary file write that can be used to execute code outside the Composer project's context in which you expected the package code to execute (for example by writing shell startup files, SSH authorized_keys, or a cron entry). It is a supply-chain issue: it requires a malicious or compromised package to be present in the dependency graph, it is not otherwise remotely exploitable against a machine.
The fix makes Composer validate every package produced by dependency resolution before anything is written to composer.lock or installed, and abort with a security error if a package name is not a valid vendor/package name.
Am I affected?
You may be affected if you install packages from an untrusted third party repository, which does not sufficiently validate package names. Packagist.org and Private Packagist are safe, as they validate package names correctly.
Patched versions
Fixed in 2.2.29 and 2.10.2. Composer 1.x is also affected and you should move to a safe 2.x release.
Workarounds
Do not use untrusted package repositories. If you have to, mirror them through an internal repository like Private Packagist.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | composer/composer | ≥ 2.3.0&&< 2.10.2 | 2.10.2composer require composer/composer:^2.10.2 |
| 🐘Packagist | composer/composer | ≥ 1.0.0&&< 2.2.29 | 2.2.29composer require composer/composer:^2.2.29 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for composer/composer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update composer/composer to 2.10.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-499r-g7pc-vmp9 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
Frequently Asked Questions
Is GHSA-499r-g7pc-vmp9 in your dependencies?
Find it across Packagist, including transitive dependencies.