{"id":"CVE-2026-54570","sourceIdentifier":"security-advisories@github.com","published":"2026-08-18T18:18:23.310","lastModified":"2026-09-18T20:09:01.757","vulnStatus":"Deferred","cveTags":[],"descriptions":[{"lang":"en","value":"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":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"AngleSharp","product":"AngleSharp","versions":[{"version":"< 1.5.0","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N","baseScore":6.9,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"CHANGED","confidentialityImpact":"LOW","integrityImpact":"HIGH","availabilityImpact":"NONE"},"exploitabilityScore":1.6,"impactScore":4.7}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-08-18T19:27:27.410295Z","id":"CVE-2026-54570","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"security-advisories@github.com","type":"Secondary","description":[{"lang":"en","value":"CWE-80"}]}],"references":[{"url":"https://github.com/AngleSharp/AngleSharp/commit/8033a5c690af9c2c443f58e34875343fa4cc1d07","source":"security-advisories@github.com"},{"url":"https://github.com/AngleSharp/AngleSharp/releases/tag/1.5.0","source":"security-advisories@github.com"},{"url":"https://github.com/AngleSharp/AngleSharp/security/advisories/GHSA-pgww-w46g-26qg","source":"security-advisories@github.com"},{"url":"https://github.com/AngleSharp/AngleSharp/security/advisories/GHSA-pgww-w46g-26qg","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}]}