Home/CVE/HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks.
CVE

CVE-2026-25543

HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks.

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.

MEDIUM · CVSS 6.1 EPSS 0.00017
Schedule remediation
  • SSVC automatable: yes - attacks can be scripted at scale
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-116Improper Encoding or Escaping of Output
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
▤

Affected Products & Versions

2
htmlsanitizer project htmlsanitizer< 9.0.892
htmlsanitizer project htmlsanitizer>= 9.1.878 and < 9.1.893
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
NuGet HtmlSanitizer MODERATE fixed in 9.0.892
▣

Scoring & Timeline

6.1
MEDIUM · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD04 Feb 2026 · 10:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

4
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/mganss/HtmlSanitizer/commit/0ac53dca30ddad963f2b243669a5066933d82b81Patch
https://github.com/mganss/HtmlSanitizer/security/advisories/GHSA-j92c-7v7g-gj3fMitigationPatchVendor Advisory
https://www.nuget.org/packages/HtmlSanitizer/9.0.892ProductRelease Notes
https://www.nuget.org/packages/HtmlSanitizer/9.1.893-betaProductRelease Notes
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