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CVE-2026-54570— AngleSharp: HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

Quick assessment

Affected
AngleSharp AngleSharp
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

AngleSharp是AngleSharp组织的一款HTML解析器库 AngleSharp 1.5.0之前版本存在跨站脚本漏洞，该漏洞源于MathAnnotationXmlElement未作为HTML集成点处理，导致DOM解析差异，攻击者可利用该差异进行突变型跨站脚本攻击。

CVSS 6.9 · Medium EPSS 0.25% · P16

Possible ATT&CK Techniques 1 AI

T1189 · Drive-by Compromise

Affected Version Matrix 1

VendorProduct Version RangeStatus
AngleSharp AngleSharp < 1.5.0 affected
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I. Basic Information for CVE-2026-54570

Vulnerability Information
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Vulnerability Title
AngleSharp: HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
Web页面中脚本相关HTML标签转义处理不恰当(基本跨站脚本)
Source: CVE Program / CVE List V5
Vulnerability Title
AngleSharp 跨站脚本漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
AngleSharp是AngleSharp组织的一款HTML解析器库 AngleSharp 1.5.0之前版本存在跨站脚本漏洞，该漏洞源于MathAnnotationXmlElement未作为HTML集成点处理，导致DOM解析差异，攻击者可利用该差异进行突变型跨站脚本攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
AngleSharp AngleSharp < 1.5.0 -

II. Public POCs for CVE-2026-54570

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III. Intelligence Information for CVE-2026-54570

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Patches & Fixes for CVE-2026-54570 (1)

Vendor Advisories for CVE-2026-54570 (1)

Vendor Pages for CVE-2026-54570 (1)

IV. Related Vulnerabilities

Same weakness: CWE-80

V. Comments for CVE-2026-54570

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