GHSA-r6hr-vr92-vv28: High severity composer/phpcsstandards/phpcsutils vulnerability
Impact
PHPCSUtils versions 1.0.0-alpha1 through 1.2.2 contain an arbitrary code execution vulnerability in PHPCSUtils\AbstractSniffs\AbstractArrayDeclarationSniff::getActualArrayKey(). The vulnerable method is reached by any sniff that extends AbstractArrayDeclarationSniff and calls getActualArrayKey().
Running PHPCS over untrusted PHP code through such a sniff, for example, in a CI pipeline that lints pull requests, or on a developer machine reviewing third-party code, could lead to arbitrary command execution on the scanning host.
The vulnerability happens when the method determines the value of an array key using eval(). A maliciously crafted array key such as 'system'('id') would be executed when the code was scanned.
Known attack vectors
Known code paths that reach the vulnerable method include the following PHPCSExtra sniffs:
- Universal.Arrays.DuplicateArrayKey - Universal.Arrays.MixedArrayKeyTypes
Other packages that call AbstractArrayDeclarationSniff::getActualArrayKey() may also be vulnerable.
Patches
This issue has been fixed in PHPCSUtils 1.2.3. We recommend all users upgrade to 1.2.3 or later.
Workaround
Users who cannot upgrade immediately can disable the sniffs that reach the vulnerable method by adding <exclude> tags to their custom ruleset (replace the placeholder standard and sniff names with the ones used in your setup):
xml <rule ref="Standard"> <exclude name="Standard.Category.SniffName"/> </rule>
For example, to disable the two PHPCSExtra sniffs listed under "Known attack vectors":
xml <rule ref="Universal"> <exclude name="Universal.Arrays.DuplicateArrayKey"/> <exclude name="Universal.Arrays.MixedArrayKeyTypes"/> </rule>
To verify that the sniffs have been disabled, run PHPCS with the -e flag, which lists all the sniffs a standard will run. The excluded sniffs should no longer appear in the output:
phpcs -e --standard=/path/to/ruleset.xml
Credits
Many thanks to @rodrigoprimo for responsibly disclosing this vulnerability.
How can I report a security bug?
Please report security vulnerabilities privately via the "Security and quality" tab on the PHPCSUtils repository.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
composer/phpcsstandards/phpcsutilsto a version that resolves this vulnerability.Fixed in 1.2.3 - Upgrade
Upgrade
PHPCSUtilsto a version that resolves this vulnerability.Fixed in 1.2.3 - Configuration
Add <exclude> tags for Universal.Arrays.DuplicateArrayKey and Universal.Arrays.MixedArrayKeyTypes to disable the vulnerable PHPCSExtra sniffs if PHPCSUtils cannot be upgraded immediately.
PHPCS custom ruleset excluded sniffs = Universal.Arrays.DuplicateArrayKey; Universal.Arrays.MixedArrayKeyTypes
Event History
Frequently Asked Questions
Which environments are most exposed to exploitation?
Environments that run PHPCS against untrusted PHP code are exposed, including CI systems that lint pull requests and developer machines used to review third-party code. Exploitation results in command execution on the host performing the scan.
What does an attacker need to do to trigger the issue?
An attacker needs to supply PHP code that is scanned by a sniff extending AbstractArrayDeclarationSniff and calling getActualArrayKey(). A malicious array key such as 'system'('id') can be executed during scanning.
Which sniffs are known to reach the vulnerable code path?
Known affected code paths include the PHPCSExtra sniffs Universal.Arrays.DuplicateArrayKey and Universal.Arrays.MixedArrayKeyTypes. Other packages may also be affected if they call AbstractArrayDeclarationSniff::getActualArrayKey().
How can I determine whether an installation needs remediation?
Installations using PHPCSUtils versions 1.0.0-alpha1 through 1.2.2 need remediation if their scanning configuration can reach getActualArrayKey(), particularly through the known PHPCSExtra sniffs. The issue is fixed in PHPCSUtils 1.2.3 and later.