TYPO3-CORE-SA-2023-002: By-passing Cross-Site Scripting Protection in HTML Sanitizer

Categories: Development, TYPO3 CMS Created by Oliver Hader
It has been discovered that TYPO3 CMS is vulnerable to cross-site scripting.

Problem Description

Due to an encoding issue in the serialization layer, malicious markup nested in a noscript element was not encoded correctly. noscript is disabled in the default configuration, but might have been enabled in custom scenarios. This allows bypassing the cross-site scripting mechanism of typo3/html-sanitizer.


Update to TYPO3 versions 8.7.53 ELTS, 9.5.42 ELTS, 10.4.39 ELTS, 11.5.30, 12.4.4 that fix the problem described above.


Thanks to David Klein and Yaniv Nizry who reported this issue, and to TYPO3 core & security team members Oliver Hader and Benjamin Franzke 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

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