Bypass of Cross-Site Scripting Protection in typo3/html-sanitizer

Vulnerability Description

The typo3/html-sanitizer package is an HTML sanitizer, written in PHP, aiming to provide XSS-safe markup based on explicitly allowed tags, attributes and values. Due to a parsing issue in the upstream package `masterminds/html5`, malicious markup used in a sequence with special HTML comments cannot be filtered and sanitized. This allows for a bypass of the cross-site scripting mechanism of `typo3/html-sanitizer`. This issue has been addressed in versions 1.0.7 and 2.0.16 of the `typo3/html-sanitizer` package. Users are advised to upgrade. There are no known workarounds for this issue.

References

• https://github.com/TYPO3/html-sanitizer/security/advisories/GHSA-47m6-46mj-p235
• https://github.com/TYPO3/html-sanitizer/commit/60bfdc7f9b394d0236e16ee4cea8372a7defa493
• https://packagist.org/packages/masterminds/html5
• https://packagist.org/packages/typo3/html-sanitizer