phpunit/phpunit security advisory

CVE-2026-41570: Argument injection via newline in PHP INI values forwarded to child processes in phpunit/phpunit

CVE-2026-41570 is a high-severity remote code execution vulnerability in the PHP package phpunit/phpunit (CVSS 7.8), published 8 May 2026. It is fixed in 12.5.22 and 13.1.6, one per release line; earlier versions on each line are affected. Exploiting it needs a low-privilege user account.

high 7.8 published 2026-05-08 · updated 2026-10-26

Affected versions: >= 12.5.21, < 12.5.22
>= 13.1.5, < 13.1.6
Fixed in: 12.5.22, 13.1.6
Newest release: 13.4.6
Severity: High · CVSS 7.8
Type: Remote code execution
CWE-88, CWE-93
Exploited in the wild: Not on the CISA KEV list
checked 2026-11-04

Is your phpunit/phpunit version affected?

Run composer show phpunit/phpunit in your project, then enter the version. We check it against this and every other known phpunit/phpunit advisory.

Who can exploit CVE-2026-41570

Access: A normal, low-privilege user account in the app.
Position: The attacker needs local access to the server.

CVSS vector (scored by GitHub): CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Your app is only exposed if it uses the affected part of phpunit/phpunit. The advisory below says which part that is. If you are not sure, upgrade anyway: it costs less than finding out.

How to fix CVE-2026-41570 in phpunit/phpunit

Find the installed version: composer show phpunit/phpunit. If you never required it yourself, composer why phpunit/phpunit shows which package pulls it in.
Update it: composer update phpunit/phpunit --with-all-dependencies. You need the fixed version for your release line (12.5.22 and 13.1.6).
If Composer will not go that high, your composer.json constraint is holding it back. Widen it (for example "phpunit/phpunit": "^13.1.6" if you can take that version), or upgrade the package that requires it.
Run composer audit. It reads the same advisory data and should no longer list CVE-2026-41570.
Commit composer.lock and deploy it. On the server, run composer install --no-dev from the lock file, not composer update.

If you cannot upgrade yet

General hardening for remote code execution issues while the upgrade waits. None of it replaces the fix.

Never pass user-controlled data to unserialize() or to template rendering, and restrict who can edit templates or settings.
Put a web application firewall in front of the app and watch for new PHP files or admin users.
If your app does not use the affected feature, note that in your audit, but still plan the upgrade.

The CVE-2026-41570 advisory

PHPUnit is a testing framework for PHP. In versions 12.5.21 and 13.1.5, PHPUnit forwards PHP INI settings to child processes (used for isolated/PHPT test execution) as -d name=value command-line arguments without neutralizing INI metacharacters. Because PHP's INI parser interprets " as a string delimiter, ; as the start of a comment, and most importantly a newline as a directive separator, a value containing a newline is parsed by the child process as multiple INI directives. An attacker able to influence a single INI value can therefore inject arbitrary additional directives into the child's configuration, including auto_prepend_file, extension, disable_functions, open_basedir, and others. Setting auto_prepend_file to an attacker-controlled path yields remote code execution in the child process. This issue has been patched in versions 12.5.22 and 13.1.6.

Description from the CVE record, published by GitHub (the CVE Numbering Authority), via the NVD entry for CVE-2026-41570. Advisory title: “Argument injection via newline in PHP INI values forwarded to child processes”.

References

GitHub security advisory GHSA-qrr6-mg7r-m243 github.com
Pull request #6592 github.com

Other phpunit/phpunit advisories

medium CVE-2026-119193: PHPUnit vulnerable to code execution by other local users via shared temporary directory in PHPT code coverage handling 2026-10-27
high PHPUnit: Argument injection via newline in PHP INI values forwarded to child processes 2026-04-22
high CVE-2026-24765: Unsafe Deserialization in PHPT Code Coverage Handling 2026-01-27
critical CVE-2017-9841: RCE vulnerability in phpunit 2016-11-13

Need help patching or upgrading? Laskyr does PHP and Laravel security fixes and upgrades. Tell us what you run and we reply with a plan and a price.

Ask about a fix

Where this data comes from

Affected and fixed versions: the Packagist security advisories API (GitHub Advisory Database and FriendsOfPHP), the same data composer audit uses. Synced 2026-11-03.
Description, score, weakness and references: NIST National Vulnerability Database (NVD), checked 2026-11-04. This product uses data from the NVD API but is not endorsed or certified by the NVD.
Exploited-in-the-wild status: the CISA Known Exploited Vulnerabilities catalog, checked 2026-11-04.
Compiled by Daniel Lasek at Laskyr from the sources above. The summary, “who can exploit it”, “how to fix it” and hardening sections are our plain-English reading of the record and are generated from it. The quoted description is the record's own text. Spot an error? Tell us.