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CVE-2026-54570

AngleSharp: HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass PUBLISHED

Description (CNA)

AngleSharp is a .NET library for parsing angle bracket based hyper-texts. Prior to 1.5.0, MathAnnotationXmlElement in AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs is not treated as an HTML integration point when its encoding attribute is text/html or application/xhtml+xml, causing Consume in AngleSharp/Html/Parser/HtmlDomBuilder.cs to route tokens through foreign-content parsing instead of HTML parsing. A sanitizer can therefore observe a different DOM from the browser that reparses the serialized output. An attacker can combine this namespace differential with markup-breaking characters in an attribute value so that an element hidden from the sanitizer becomes active script-capable HTML after browser reparse, resulting in mutation cross-site scripting. This issue is fixed in version 1.5.0.

Affected (CNA)

Vendor / productVersions
AngleSharp / AngleSharpaffected < 1.5.0

CWE

CWE-80

References

ADP enrichment

CISA-ADP

No English description supplied.