CVE-2026-24765

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.

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.

Overview

A vulnerability has been discovered 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.

Technical Details

Affected Component: PHPT test runner, method cleanupForCoverage() Affected Versions: <= 8.5.51, <= 9.6.32, <= 10.5.61, <= 11.5.49, <= 12.5.7

Vulnerable Code Pattern

if ($buffer !== false) {
    // Unsafe call without restrictions
    $coverage = @unserialize($buffer);
}

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.

Attack Prerequisites and Constraints

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: A malicious pull request that places a .coverage file alongside test files, executed when the CI system runs tests using PHPUnit and collects code coverage information
• Local Development Environment: An attacker with shell access or ability to write files to the project directory
• Compromised Dependencies: A supply chain attack inserting malicious files into a package or monorepo

Critical Context: Running test suites from unreviewed pull requests without isolated execution is inherently a code execution risk, independent of this specific vulnerability. This represents a broader class of Poisoned Pipeline Execution (PPE) attacks affecting CI/CD systems.

Proposed Remediation Approach

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.

Rationale for Error-Based Approach:

1. Visibility Over Silence: When an invariant is violated (a .coverage file existing before test execution), the error must be visible in CI/CD output, alerting operators to investigate the root cause rather than proceeding with sanitized input
2. Operational Security: A .coverage file should never exist before tests run, coverage data is generated by executing tests, not sourced from artifacts. Its presence indicates:
   • A malicious actor placed it intentionally
   • Build artifacts from a previous run contaminated the environment
   • An unexpected filesystem state requiring investigation
3. Defense-in-Depth Principle: Protecting a single deserialization call does not address the fundamental attack surface. Proper mitigations for PPE attacks lie outside PHPUnit's scope:
   • Isolate CI/CD runners (ephemeral, containerized environments)
   • Restrict code execution on protected branches
   • Scan pull requests and artifacts for tampering
   • Use branch protection rules to prevent unreviewed code execution

Severity Classification

• Attack Vector (AV): Local (L) — requires write access to the file system where tests execute
• Attack Complexity (AC): Low (L) — exploitation is straightforward once the malicious file is placed
• Privileges Required (PR): Low (L) — PR submitter status or contributor role provides sufficient access
• User Interaction (UI): None (N) — automatic execution during standard test execution
• Scope (S): Unchanged (U) — impact remains within the affected test execution context…

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.

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.

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.