How severe is CVE-2026-25543?

CVE-2026-25543 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-25543 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-25543?

CVE-2026-25543 affects Htmlsanitizer Project Htmlsanitizer. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-25543?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-25543 have an EU (EUVD) identifier?

Yes. CVE-2026-25543 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5328.

When was CVE-2026-25543 published?

CVE-2026-25543 was published on 2026-02-04 and last updated on 2026-06-17.

CVE-2026-25543

CVE-2026-25543 is a medium-severity vulnerability in Htmlsanitizer Project Htmlsanitizer with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v4: 6.3
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-5328
Weakness: CWE-79
Affected product: Htmlsanitizer Project Htmlsanitizer
Published: 2026-02-04
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-25543?: 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.
How severe is CVE-2026-25543?: CVE-2026-25543 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-25543 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-25543?: CVE-2026-25543 affects Htmlsanitizer Project Htmlsanitizer. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-25543?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-25543 have an EU (EUVD) identifier?: Yes. CVE-2026-25543 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5328.
When was CVE-2026-25543 published?: CVE-2026-25543 was published on 2026-02-04 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:htmlsanitizer_project:htmlsanitizer:*:*:*:*:*:*:*:*

More vulnerabilities in Htmlsanitizer Project Htmlsanitizer

CVE-2023-44390 — Medium (CVSS 6.1): HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks.…
CVE-2020-26293 — Medium (CVSS 6.1): HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks.…

All CVEs affecting Htmlsanitizer Project Htmlsanitizer →

Other CWE-79 (Cross-site Scripting (XSS)) vulnerabilities

CVE-2025-49410 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Imran Emu TC…
CVE-2024-47875 — Critical (CVSS 10.0): DOMPurify is a DOM-only, super-fast, uber-tolerant XSS sanitizer for HTML, MathML and SVG. DOMpurify was vulnerable to…
CVE-2024-6886 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Gitea…
CVE-2023-45144 — Critical (CVSS 10.0): com.xwiki.identity-oauth:identity-oauth-ui is a package to aid in building identity and service providers based on…
CVE-2023-45138 — Critical (CVSS 10.0): Change Request is an pplication allowing users to request changes on a wiki without publishing the changes directly.…
CVE-2022-4361 — Critical (CVSS 10.0): Keycloak, an open-source identity and access management solution, has a cross-site scripting (XSS) vulnerability in the…

Browse all CWE-79 (Cross-site Scripting (XSS)) vulnerabilities →