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CVE-2026-25543

21
FAUCET Score

CVE-2026-25543 is a medium-severity cross-site scripting (XSS) vulnerability affecting HtmlSanitizer, a .NET library designed to clean HTML. Prior to versions 9.0.892 and 9.1.893-beta, the library failed to sanitize the contents of the 'template' tag, which could be exploited if the 'shadowrootmode' attribute was set. This vulnerability has a CVSS score of 6.1, indicating a network-based attack requiring user interaction, with potential for low impact on confidentiality and integrity. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 9.0.892CPE matchmatch criteria
cpe:2.3:a:htmlsanitizer_project:htmlsanitizer:*:*:*:*:*:*:*:*
>= 9.1.878, < 9.1.893CPE matchmatch criteria
cpe:2.3:a:htmlsanitizer_project:htmlsanitizer:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

6.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
VS Confidentiality
NONE
VS Integrity
NONE
VS Availability
NONE
SS Confidentiality
LOW
SS Integrity
LOW
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.24%
Probability of exploitation in next 30 days
EPSS Percentile
15.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0024 is in the 16th percentile among its peer group of 26,221 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

github_advisorypatch availablevia nvd_reference
View patch
nugetpatch availablevia ghsa
Product: HtmlSanitizerFixed in: 9.0.892
nugetpatch availablevia ghsa
Product: HtmlSanitizerFixed in: 9.1.893-beta

Vendor Advisories (1)

nugetGHSA-j92c-7v7g-gj3fmedium

HtmlSanitizer has a bypass via template tag

Feb 3, 2026

References

github.com / mganss/HtmlSanitizer/commit/0ac53dca30ddad963f2b243669a5066933d82b81
Patch
github.com / mganss/HtmlSanitizer/security/advisories/GHSA-j92c-7v7g-gj3f
MitigationPatchVendor Advisory
nuget.org / packages/HtmlSanitizer/9.0.892
ProductRelease Notes
nuget.org / packages/HtmlSanitizer/9.1.893-beta
ProductRelease Notes