GHSA-r6hr-vr92-vv28

### 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](https://github.com/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](https://github.com/PHPCSStandards/PHPCSUtils/security).