CVE-2022-23499: Cross-Site Scripting Protection bypass in HTML Sanitizer

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-12-13 · updated 2026-06-17
Weakness: CWE-79

Description

HTML sanitizer is written in PHP, aiming to provide XSS-safe markup based on explicitly allowed tags, attributes and values. In versions prior to 1.5.0 or 2.1.1, malicious markup used in a sequence with special HTML CDATA sections cannot be filtered and sanitized due to a parsing issue in the upstream package masterminds/html5. This allows bypassing the cross-site scripting mechanism of typo3/html-sanitizer. The upstream package masterminds/html5 provides HTML raw text elements (`script`, `style`, `noframes`, `noembed` and `iframe`) as DOMText nodes, which were not processed and sanitized further. None of the mentioned elements were defined in the default builder configuration, that's why only custom behaviors, using one of those tag names, were vulnerable to cross-site scripting. This issue has been fixed in versions 1.5.0 and 2.1.1.

Affected products

TYPO3 html-sanitizer: from 1.0.0 through 1.0.7; from 2.0.0 before 2.1.1 — fixed in 2.1.1

How to fix

Upgrade to a fixed version: TYPO3 html-sanitizer 2.1.1. Check the vendor advisory for mitigations.

References

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