CVE-2026-54570
MEDIUMDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 16% of all known CVEs.
References
Related Vulnerabilities
Other CWE-80 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-21145 | Medium | 4.8 | 78% | - | - |
| CVE-2020-13562 | Medium | 6.1 | 78% | - | - |
| CVE-2020-13965 | Medium | 6.1 | 77% | KEV | Fix |
| CVE-2020-13564 | Medium | 6.1 | 76% | - | - |
| CVE-2020-13563 | Medium | 6.1 | 76% | - | - |
| CVE-2024-4439 | High | 7.2 | 71% | - | Fix |
Common questions
How do I fix CVE-2026-54570?
No published fix for CVE-2026-54570 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-54570 being actively exploited?
Not that we know of. CVE-2026-54570 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.25% is the estimated probability that it will be exploited in the next 30 days. That is higher than 16% of all scored CVEs.
How severe is CVE-2026-54570?
CVE-2026-54570 has a CVSS v3 base score of 6.9, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-18.