RCE in Shivammathur Setup-Php
CVE-2026-46420
setup-php is a GitHub action to set up PHP with extensions, php.ini configuration, coverage drivers, and tools. From 2.25.0 prior to 2.37.1, shivammathur/setup-php resolves the PHP version from repository-controlled files such as .php-version, composer.lock through platform-overrides.php, and composer.json through config.platform.php, and insufficiently constrains those values before incorporating them into generated shell or PowerShell setup scripts, allowing command injection on a GitHub Actions runner when workflows such as pull_request_target check out attacker-controlled contents before invoking setup-php. This issue is fixed in version 2.37.1.
Vulnerability class: Command Injection (OS Command Injection)
EPSS: 0.015 (73.1th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.6 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L.
Affected products
- Shivammathur Setup-php — versions >= 2.25.0, < 2.37.1
- Shivammathur Setup_php
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (Product, x_refsource_MISC, Release Notes)
- security-advisories@github.com (x_refsource_CONFIRM, Patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-46420?
- CVE-2026-46420 is a medium-severity vulnerability in Shivammathur Setup-Php, classified under OS Command Injection. CVSS score: 5.6/10. Published 2026-07-17.
- How severe is CVE-2026-46420?
- Medium severity. CVSS v3 base score is 5.6 out of 10.
- Is CVE-2026-46420 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.