CVE-2026-46420: setup-php is a GitHub action to set up PHP with extensions, php.ini configuration, coverage drivers, and tools

This month

MEDIUM 5.6REMOTEUPGRADE

CVE-2026-46420 is a medium-severity flaw (CVSS 5.6) affecting setup php. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 scr

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.6 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	2.0% (top 19%)
CISA exploited list	No
Weakness	CWE-78
Published	2026-07-17
Last modified	2026-10-24

Publisher (CNA): GitHub, Inc. · Vendor: shivammathur

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-17 20:17 UTCPublished CVE record published
2026-10-24 20:10 UTCUpdated Record last modified

shivammathur setup php UPGRADE

Affected: >= 2.25.0 and < 2.37.1

Fixed in: 2.37.1

Safe to downgrade to: a release before 2.25.0

1. Check installed version

apt-cache policy setup-php || rpm -q setup-php || setup-php --version

2. UPGRADE to 2.37.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade setup-php

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade setup-php

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.25.0 (Debian / Ubuntu)

apt-cache madison setup-php sudo apt install setup-php=<VERSION_BEFORE_2.25.0> sudo apt-mark hold setup-php

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list setup-php sudo dnf downgrade setup-php-<VERSION_BEFORE_2.25.0> sudo dnf versionlock add setup-php

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-46420?

setup php: upgrade to 2.37.1. Exact commands for each OS are on this page.

Is CVE-2026-46420 being exploited?

CVE-2026-46420 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-46420 affect?

CVE-2026-46420 affects setup php. Severity is medium (CVSS 5.6). 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-versi

How urgent is CVE-2026-46420?

Priority 45/100. Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities · GitHub vulnerabilities · PowerShell vulnerabilities

References

← Back to latest CVEs