CVE-2026-54570 json
AngleSharp: HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass
published 2026-07-17 3 mo ago modified 2026-09-18 51 d ago also GHSA-pgww-w46g-26qg , EUVD-2026-61128
- cvss
- 6.9
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 26%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- nuget AngleSharp 1.5.0
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 2 mo ago
Exploit prediction
0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/AngleSharp/AngleSharp/security/advisories/GHSA-pgww-w46g-26qg referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.9 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N |
| GitHub | 3.1 | 6.9 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| nuget | AngleSharp | <1.5.0 |
1.5.0 |
Affected products
- AngleSharp AngleSharp
Classification
- Weakness
-
- CWE-80 Improper Neutralization of Script-Related HTML Tags in a Web Page
References
Sources
- CVE List CVE-2026-54570
- GitHub Advisory GHSA-pgww-w46g-26qg
- NVD CVE-2026-54570
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