CVE-2026-84361: Composer arbitrary command execution via a malicious package's Perforce source URL

high Affects composer/composer. Feed 2026.10.29.4, updated 2026-10-29; published 2026-09-08.

Composer arbitrary command execution via a malicious package's Perforce source URL

Package: composer/composer Composer
Affected versions: >=2.3.0 and <2.10.3 or >=1.0 and <2.2.30
Fixed in: 2.10.3, 2.2.30
Severity: high
Exploitation: not on CISA KEV · EPSS 1% (42.9th percentile)
Published: 2026-09-08
Source: osv.dev

References

Am I affected?

Find out in one command. phpwarden checks your composer.lock against this advisory and 20,000+ others, ranked by real-world exploitation (CISA KEV + EPSS). Free, offline, open data.

# PHP projects (recommended)
composer require --dev phpwarden/phpwarden
# then
vendor/bin/phpwarden deps composer.lock

# or, without Composer
pipx install phpwarden   &&   phpwarden deps composer.lock

Or keep it checked automatically: GitHub Action · pre-commit hook · GitLab CI · Laravel artisan command

Install docs How findings are ranked

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