What’s Vulnerable › Vulnerabilities

CVE-2023-38500: By-passing Cross-Site Scripting Protection 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: 2023-07-25 · updated 2026-06-17
• Weakness: CWE-79

Description

TYPO3 HTML Sanitizer is an HTML sanitizer, written in PHP, aiming to provide cross-site-scripting-safe markup based on explicitly allowed tags, attributes and values. Starting in version 1.0.0 and prior to versions 1.5.1 and 2.1.2, 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. Versions 1.5.1 and 2.1.2 fix the problem.

Affected products

• TYPO3 html-sanitizer: from 1.0.0 before 1.5.1; from 2.0.0 before 2.1.2 — fixed in 1.5.1, 2.1.2

How to fix

Upgrade to a fixed version: TYPO3 html-sanitizer 1.5.1, 2.1.2. Check the vendor advisory for mitigations.

References

• https://github.com/TYPO3/html-sanitizer/commit/e3026f589fef0be8c3574ee3f0a0bfbe33d7ebdb
• https://github.com/TYPO3/html-sanitizer/security/advisories/GHSA-59jf-3q9v-rh6g
• https://typo3.org/security/advisory/typo3-core-sa-2023-002
• https://github.com/TYPO3/html-sanitizer/commit/e3026f589fef0be8c3574ee3f0a0bfbe33d7ebdb
• https://github.com/TYPO3/html-sanitizer/security/advisories/GHSA-59jf-3q9v-rh6g
• https://typo3.org/security/advisory/typo3-core-sa-2023-002

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