What is CVE-2020-26293?

HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks. In HtmlSanitizer before version 5.0.372, there is a possible XSS bypass if style tag is allowed. If you have explicitly allowed the ` ` tag, an attacker could craft HTML that includes script after passing through the sanitizer. The default settings disallow the ` ` tag so there is no risk if you have not explicitly allowed the ` ` tag. The problem has been fixed in version 5.0.372.

How severe is CVE-2020-26293?

CVE-2020-26293 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2020-26293 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-26293?

CVE-2020-26293 affects Htmlsanitizer Project Htmlsanitizer. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-26293?

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

When was CVE-2020-26293 published?

CVE-2020-26293 was published on 2021-01-04 and last updated on 2026-06-17.

CVE-2020-26293

CVE-2020-26293 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 v2: 4.3
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Htmlsanitizer Project Htmlsanitizer
Published: 2021-01-04
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. In HtmlSanitizer before version 5.0.372, there is a possible XSS bypass if style tag is allowed. If you have explicitly allowed the `<style>` tag, an attacker could craft HTML that includes script after passing through the sanitizer. The default settings disallow the `<style>` tag so there is no risk if you have not explicitly allowed the `<style>` tag. The problem has been fixed in version 5.0.372.

Frequently asked questions

What is CVE-2020-26293?: HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks. In HtmlSanitizer before version 5.0.372, there is a possible XSS bypass if style tag is allowed. If you have explicitly allowed the `<style>` tag, an attacker could craft HTML that includes script after passing through the sanitizer. The default settings disallow the `<style>` tag so there is no risk if you have not explicitly allowed the `<style>` tag. The problem has been fixed in version 5.0.372.
How severe is CVE-2020-26293?: CVE-2020-26293 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2020-26293 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-26293?: CVE-2020-26293 affects Htmlsanitizer Project Htmlsanitizer. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-26293?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-26293 published?: CVE-2020-26293 was published on 2021-01-04 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-2026-25543 — Medium (CVSS 6.1): HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to XSS attacks.…
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.…

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 →