CVE-2026-46420: Command Injection (CVSS 5.6)

Description

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.

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CVSS v3.1 Score

5.6

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

EPSS — Exploit Prediction

0.0085

Probability of exploitation

0.54%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-78 OS Command Injection

References

Other References

https://github.com/shivammathur/setup-php/commit/eeef37e059fb5368a5bc8ed8ce45ff54bd39b80b https://github.com/shivammathur/setup-php/releases/tag/2.37.1 https://github.com/shivammathur/setup-php/security/advisories/GHSA-pqwm-q9pv-ph8r

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 5.6 (MEDIUM).

How severe is CVE-2026-46420? +

CVE-2026-46420 has a CVSS v3.1 score of 5.6 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0085, placing it in the 1th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-46420? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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