{"id":"CVE-2026-54570","state":"PUBLISHED","title":"AngleSharp: HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass","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.","publishedAt":"2026-08-18T17:39:51.827Z","updatedAt":"2026-08-18T19:27:44.943Z","severity":{"score":6.9,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["AngleSharp AngleSharp"],"affected":[{"vendor":"AngleSharp","product":"AngleSharp","versions":[{"version":"< 1.5.0","status":"affected"}]}],"references":["https://github.com/AngleSharp/AngleSharp/security/advisories/GHSA-pgww-w46g-26qg","https://github.com/AngleSharp/AngleSharp/commit/8033a5c690af9c2c443f58e34875343fa4cc1d07","https://github.com/AngleSharp/AngleSharp/releases/tag/1.5.0"],"weaknesses":["CWE-80"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/54xxx/CVE-2026-54570.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-54570","state":"PUBLISHED","datePublished":"2026-08-18T17:39:51.827Z","dateUpdated":"2026-08-18T19:27:44.943Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-15T19:15:27.343Z"},"containers":{"cna":{"title":"AngleSharp: HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass","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":[{"vendor":"AngleSharp","product":"AngleSharp","versions":[{"version":"< 1.5.0","status":"affected"}]}],"references":[{"url":"https://github.com/AngleSharp/AngleSharp/security/advisories/GHSA-pgww-w46g-26qg","name":"https://github.com/AngleSharp/AngleSharp/security/advisories/GHSA-pgww-w46g-26qg","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/AngleSharp/AngleSharp/commit/8033a5c690af9c2c443f58e34875343fa4cc1d07","name":"https://github.com/AngleSharp/AngleSharp/commit/8033a5c690af9c2c443f58e34875343fa4cc1d07","tags":["x_refsource_MISC"]},{"url":"https://github.com/AngleSharp/AngleSharp/releases/tag/1.5.0","name":"https://github.com/AngleSharp/AngleSharp/releases/tag/1.5.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.9,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-80","lang":"en","description":"CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-18T17:39:51.827Z"},"source":{"advisory":"GHSA-pgww-w46g-26qg","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/AngleSharp/AngleSharp/security/advisories/GHSA-pgww-w46g-26qg","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-18T19:27:27.410295Z","id":"CVE-2026-54570","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-18T19:27:44.943Z"}}]}}}