AngleSharp up to 1.4.x HTML Parser HtmlDomBuilder.cs Consume encoding HTML injection

Summaryinfo

A vulnerability, which was classified as problematic, was found in AngleSharp up to 1.4.x. This issue affects the function Consume of the file AngleSharp/Html/Parser/HtmlDomBuilder.cs of the component HTML Parser. The manipulation of the argument encoding results in HTML injection. This vulnerability is known as CVE-2026-54570. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability, which was classified as problematic, was found in AngleSharp up to 1.4.x. Affected is the function Consume of the file AngleSharp/Html/Parser/HtmlDomBuilder.cs of the component HTML Parser. The manipulation of the argument encoding with an unknown input leads to a html injection vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-54570 since 06/15/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project.

Upgrading to version 1.5.0 eliminates this vulnerability.

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Productinfo

Name

• AngleSharp

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4

Website

• Product: https://github.com/AngleSharp/AngleSharp/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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