CVE-2026-25543
HtmlSanitizer has a bypass via template tag
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.
INFO
Published Date :
Feb. 4, 2026, 10:16 p.m.
Last Modified :
Feb. 4, 2026, 10:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-25543
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update HtmlSanitizer to version 9.0.892 or later.
- Update HtmlSanitizer to version 9.1.893-beta or later.
- Ensure template tag contents are sanitized if allowed.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-25543.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-25543 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-25543
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-25543 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-25543 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Feb. 04, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 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 Added CWE CWE-116 Added Reference https://github.com/mganss/HtmlSanitizer/commit/0ac53dca30ddad963f2b243669a5066933d82b81 Added Reference https://github.com/mganss/HtmlSanitizer/security/advisories/GHSA-j92c-7v7g-gj3f Added Reference https://www.nuget.org/packages/HtmlSanitizer/9.0.892 Added Reference https://www.nuget.org/packages/HtmlSanitizer/9.1.893-beta