CVE-2026-24765
HIGHPHPUnit Vulnerable to Unsafe Deserialization in PHPT Code Coverage Handling
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
phpunit/phpunit🐘phpunit/phpunit🐘phpunit/phpunit🐘phpunit/phpunit🐘phpunit/phpunitReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
PHPUnit is a testing framework for PHP. A vulnerability has been discovered in versions prior to 12.5.8, 11.5.50, 10.5.62, 9.6.33, and 8.5.52 involving unsafe deserialization of code coverage data in PHPT test execution. The vulnerability exists in the cleanupForCoverage() method, which deserializes code coverage files without validation, potentially allowing remote code execution if malicious .coverage files are present prior to the execution of the PHPT test. The vulnerability occurs when a .coverage file, which should not exist before test execution, is deserialized without the allowed_classes parameter restriction. An attacker with local file write access can place a malicious serialized object with a __wakeup() method into the file system, leading to arbitrary code execution during test runs with code coverage instrumentation enabled. This vulnerability requires local file write access to the location where PHPUnit stores or expects code coverage files for PHPT tests. This can occur through CI/CD pipeline attacks, the local development environment, and/or compromised dependencies. Rather than just silently sanitizing the input via ['allowed_classes' => false], the maintainer has chosen to make the anomalous state explicit by treating pre-existing .coverage files for PHPT tests as an error condition. Starting in versions in versions 12.5.8, 11.5.50, 10.5.62, 9.6.33, when a .coverage file is detected for a PHPT test prior to execution, PHPUnit will emit a clear error message identifying the anomalous state. Organizations can reduce the effective risk of this vulnerability through proper CI/CD configuration, including ephemeral runners, code review enforcement, branch protection, artifact isolation, and access control.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | phpunit/phpunit | all versions | 8.5.52 |
| 🐘Packagist | phpunit/phpunit | ≥ 9.0.0&&< 9.6.33 | 9.6.33 |
| 🐘Packagist | phpunit/phpunit | ≥ 10.0.0&&< 10.5.62 | 10.5.62 |
| 🐘Packagist | phpunit/phpunit | ≥ 11.0.0&&< 11.5.50 | 11.5.50 |
| 🐘Packagist | phpunit/phpunit | ≥ 12.0.0&&< 12.5.8 | 12.5.8 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for phpunit/phpunit. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update phpunit/phpunit to 8.5.52 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-24765 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-24765 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-24765. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-24765 in your dependencies?
O3 detects CVE-2026-24765 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.