By-passing Cross-Site Scripting Protection in HTML Sanitizer
Date: 2023-07
Affected: composer/typo3/html-sanitizer, composer/typo3/html-sanitizer
Attack vector: xss
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2023-38500
CWE: CWE-79
CVSS: 4.7 (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N)

> ### CVSS: `CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC:C` (4.4) ### Problem 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`](https://packagist.org/packages/typo3/html-sanitizer). ### Solution Update to `typo3/html-sanitizer` versions 1.5.1 or 2.1.2 that fix the problem described. ### Credits Thanks to David Klein and Yaniv Nizry who reported this issue, and to TYPO3 security team members Oliver Hader and Benjamin Franzke who fixed the issue. ### References * [TYPO3-CORE-SA-2023-002](https://typo3.org/security/advisory/typo3-core-sa-2023-002)


Mitigations:

Architectural layers (MAESTRO):