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CVE-2026-54570

AngleSharp is a .NET library for parsing angle bracket based hyper-texts. Prior to 1.5.0,…

CVSS 3.1 · [email protected] · Secondary 6.9 MEDIUMCheck source for fixed versionsKEV status unknown
Original advisory

Historical advisory recorded 25 Oct 2026 13:17:28 UTC. Read the latest advisory.

nvd · CVE-2026-54570

Published

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.

Read the publisher's advisory

Affected versions, risk and source history

nvd · CVE-2026-54570

Published

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 a…

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.

Additional publisher context

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Deferred

Weakness classifications: CWE-80

Original publisher date fields

published: 2026-08-18T18:18:23.310

lastModified: 2026-09-18T20:09:01.757

Source published
18 Aug 2026 18:18:23 UTC
Source modified
18 Sep 2026 20:09:01 UTC
Saved here
25 Oct 2026 13:17:28 UTC
Source terms
NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · [email protected] · Secondary · 6.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N

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Sources read 15 Nov 01:41 UTC · 255 of 275 readable · 253 fully read · documentation 469/469 current

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