OS Command Injection in shivammathur/setup-php (CVE-2026-46420)
Summary
OS command injection in shivammathur/setup-php (CVE-2026-46420). Risk of unauthorized operations or information disclosure. Exploitable via composer.lock. Mitigation: upgrade to 2.37.1 or later.
Original description
The description as published by the source.
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.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-46420 has been found in shivammathur/setup-php.
Attackers can target a specific entry point like composer.lock over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.6/10.
What to do: upgrade shivammathur/setup-php to 2.37.1 or later.
If unsure, ask your IT team or search "shivammathur/setup-php CVE-2026-46420" on the vendor's site.
CVE-2026-46420 (shivammathur/setup-php) — CWE-78 / CVSS v3 5.6
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: composer.lock / config.platform.php / pull_request_target
Patched: 2.37.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
OS command injection (CWE-78) exists in shivammathur/setup-php. Attackers reach the vulnerable code path via composer.lock without authentication.
Check the vendor advisory for the affected versions of shivammathur/setup-php. Attack surface: composer.lock / config.platform.php / pull_request_target.
Severity: Medium (CVSS 5.6/10). Risk of unauthorized operations or information disclosure.
Update to 2.37.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'shivammathur/setup-php' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'shivammathur/setup-php' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
shivammathur/setup-phpを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade shivammathur/setup-php to 2.37.1ステージング環境で 2.37.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- patch github.com
- web github.com
- web github.com