CVE-2026-25543 MEDIUM

CVE-2026-25543: HtmlSanitizer has a bypass via template tag

Vendor Mganss
Product HtmlSanitizer
Weakness CWE-116
Published February 4, 2026
Last update February 5, 2026
View on NVD All CVEs

CVSS base score

6.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

February 4, 2026 CVE published
February 5, 2026 Record updated