mganss HtmlSanitizer up to 9.0.891 cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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5.1$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic has been found in mganss HtmlSanitizer up to 9.0.891. Affected by this issue is some unknown functionality. This manipulation causes cross site scripting. This vulnerability is registered as CVE-2026-25543. Remote exploitation of the attack is possible. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in mganss HtmlSanitizer up to 9.0.891. It has been declared as problematic. Affected by this vulnerability is some unknown processing. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-25543 since 02/02/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

Upgrading to version 9.0.892 or 9.1.893-beta eliminates this vulnerability. Applying the patch 0ac53dca30ddad963f2b243669a5066933d82b81 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-5328). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.2
VulDB Meta Temp Score: 5.1

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 6.1
NVD Vector: 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: HtmlSanitizer 9.0.892/9.1.893-beta
Patch: 0ac53dca30ddad963f2b243669a5066933d82b81

Timelineinfo

02/02/2026 CVE reserved
02/05/2026 +3 days Advisory disclosed
02/05/2026 +0 days VulDB entry created
02/26/2026 +21 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-j92c-7v7g-gj3f
Status: Confirmed

CVE: CVE-2026-25543 (🔒)
GCVE (CVE): GCVE-0-2026-25543
GCVE (VulDB): GCVE-100-344455
EUVD: 🔒

Entryinfo

Created: 02/05/2026 07:57
Updated: 02/26/2026 12:45
Changes: 02/05/2026 07:57 (69), 02/05/2026 09:16 (1), 02/26/2026 12:45 (12)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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