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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-54570
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-18 18:18:23 UTC
Updated2026-08-18 20:17:18 UTC
DescriptionAngleSharp 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.

Risk And Classification

Primary CVSS: v3.1 6.9 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N

Problem Types: CWE-80 | CWE-80 CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N
3.1CNADECLARED6.9MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA AngleSharp AngleSharp affected < 1.5.0 Not specified

References

ReferenceSourceLinkTags
github.com/AngleSharp/AngleSharp/security/advisories/GHSA-pgww-w46g-26qg 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/AngleSharp/AngleSharp/releases/tag/1.5.0 [email protected] github.com
github.com/AngleSharp/AngleSharp/commit/8033a5c690af9c2c443f58e34875343f... [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report