Problem Description

Due to a parsing issue in upstream package masterminds/html5, malicious markup used in a sequence with special HTML comments cannot be filtered and sanitized. This allows to by-pass the cross-site scripting mechanism of typo3/html-sanitizer.

Solution

Update to TYPO3 version 7.6.58 ELTS, 8.7.48 ELTS, 9.5.37 ELTS, 10.4.32 or 11.5.16 that fix the problem described above.

Credits

Thanks to David Klein who reported this issue, and to TYPO3 security team member Oliver Hader who fixed the issue.

General Advice

Follow the recommendations that are given in the TYPO3 Security Guide. Please subscribe to the typo3-announce mailing list.

General Note

All security related code changes are tagged so that you can easily look them up in our review system.