title: Cross-Site Scripting Protection bypass in HTML Sanitizer
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.
problem types: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
affected:
{
vendor: TYPO3
product: html-sanitizer
versions:
version: >= 1.0.0, < 1.5.0, status: affected
version: >= 2.0.0, < 2.1.1, status: affected
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 6.1
baseSeverity: MEDIUM
confidentialityImpact: LOW
integrityImpact: LOW
privilegesRequired: NONE
scope: CHANGED
userInteraction: REQUIRED
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
version: 3.1
]