CVE-2026-25543

Name: CVE-2026-25543
Creator: NVD / NIST
Published: 2026-02-04T22:16:00.523+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.3/10EPSS 0.24%

Last modified Jun 17, 2026

CVE-2026-25543 is a medium-severity vulnerability rated 6.3/10 on the CVSS scale. HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks. Prior to versions 9.0.892 and 9.1.893-beta, if the template tag is allowed, its contents are not sanitized. EPSS estimates a 0.24% chance of exploitation in the next 30 days.

Description

HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks. Prior to versions 9.0.892 and 9.1.893-beta, if the template tag is allowed, its contents are not sanitized. The template tag is a special tag that does not usually render its contents, unless the shadowrootmode attribute is set to open or closed. This issue has been patched in versions 9.0.892 and 9.1.893-beta.

Metrics

CVSS 3.1

6.1/10

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

CVSS 4.0

6.3/10

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability

0.24%

15.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Htmlsanitizer Project	Htmlsanitizer	< 9.0.892
Htmlsanitizer Project	Htmlsanitizer	>= 9.1.878, < 9.1.893

References

https://github.com/mganss/HtmlSanitizer/commit/0ac53dca30ddad963f2b243669a5066933d82b81Patch
https://github.com/mganss/HtmlSanitizer/security/advisories/GHSA-j92c-7v7g-gj3fMitigation, Patch, Vendor Advisory
https://www.nuget.org/packages/HtmlSanitizer/9.0.892Product, Release Notes
https://www.nuget.org/packages/HtmlSanitizer/9.1.893-betaProduct, Release Notes

Timeline

Published: Feb 4, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-25543?

How severe is CVE-2026-25543?

CVE-2026-25543 has a CVSS score of 6.3/10 (MEDIUM severity). The EPSS model estimates a 0.24% probability of exploitation in the next 30 days.

How do I fix CVE-2026-25543?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-25543?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST