HtmlSanitizer vulnerable to Cross-site Scripting in Foreign Content

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS

• CVE-2023-44390: 0.42% estimated exploitation activity in the next 30 days; percentile 35.93 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

4 Oct 2023, 18:52 UTC

Last modified by the source

9 Nov 2023, 05:01 UTC

Source last checked

26 Oct 2026, 17:00 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-43cp-6p3q-2pc4

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# Patch Next advisory brief: CVE-2023-44390

Advisory: HtmlSanitizer vulnerable to Cross-site Scripting in Foreign Content
IDs: CVE-2023-44390, GHSA-43cp-6p3q-2pc4
Record: https://patchnext.com/advisories/cve-2023-44390 (revision 1, source checked 26 Oct 2026, 17:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: htmlsanitizer 8.1.722-beta, 8.0.723. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet htmlsanitizer: affected < 8.0.723; >= 8.1.0-beta, < 8.1.722-beta; fixed in 8.0.723, 8.1.722-beta

## Suggested inspection (read-only)
- NuGet htmlsanitizer: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on htmlsanitizer.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-43cp-6p3q-2pc4 (GitHub-reviewed advisory GHSA-43cp-6p3q-2pc4 lists affected ranges: NuGet htmlsanitizer >=0 =8.1.0-beta <8.1.722-beta)

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