HtmlSanitizer vulnerable to Cross-site Scripting in Foreign Content
Date: 2023-10
Affected: nuget/HtmlSanitizer, nuget/HtmlSanitizer
Attack vector: xss
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2023-44390
CWE: CWE-79
CVSS: 6.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)

### Impact The vulnerability occurs in configurations where foreign content is allowed, i.e. either `svg` or `math` are in the list of allowed elements. Specifically, the requirements for the vulnerability are: 1. Allowing one foreign element: `svg`, or `math` 2. Comments or one raw text element: `iframe`, `noembed`, `xmp`, `title`, `noframes`, `style` or `noscript` Configurations that meet the above requirements plus the following are vulnerable to an additional vulnerability: - Any HTML integration element: `title`, `desc`, `mi`, `mo`, `mn`, `ms`, `mtext`, `annotation-xml`. In case an application sanitizes user input with a vulnerable configuration, an attacker could bypass the sanitization and inject arbitrary HTML, including JavaScript code. Note that in the default configuration the vulnerability is not present. ### Patches The vulnerability has been fixed in versions 8.0.723 and 8.1.722-beta (preview version). ### Workarounds Disallow foreign elements `svg` and `math`. This is the case in the default configuration, which is therefore not affected by the vulnerability.


Mitigations:

Architectural layers (MAESTRO):