How to fix CVE-2025-66021?

Within 7 days: Identify all affected systems running web applications while protecting against XSS. In and apply vendor patches promptly. Verify anti-CSRF tokens and content security policies are enforced.

Is Java affected by CVE-2025-66021?

Organizations using web applications while protecting against XSS. In face significant risk from CVE-2025-66021, a cross-site scripting vulnerability rated CVSS 8.6. Attackers could inject malicious scripts to steal user sessions, credentials, or perform actions on behalf of authenticated users.

CVE-2025-66021

HIGH

2025-11-26 [email protected]

8.6

CVSS 4.0

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/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

Privileges Required

None

User Interaction

Scope

Lifecycle Timeline

Patch Released

Mar 31, 2026 - 21:13 nvd

Patch available

Analysis Generated

Mar 28, 2026 - 19:24 vuln.today

PoC Detected

Dec 30, 2025 - 16:34 vuln.today

Public exploit code

CVE Published

Nov 26, 2025 - 02:15 nvd

HIGH 8.6

Description

OWASP Java HTML Sanitizer is a configureable HTML Sanitizer written in Java, allowing inclusion of HTML authored by third-parties in web applications while protecting against XSS. In version 20240325.1, OWASP java html sanitizer is vulnerable to XSS if HtmlPolicyBuilder allows noscript and style tags with allowTextIn inside the style tag. This could lead to XSS if the payload is crafted in such a way that it does not sanitise the CSS and allows tags which is not mentioned in HTML policy. At time of publication no known patch is available.

Analysis

OWASP Java HTML Sanitizer is a configureable HTML Sanitizer written in Java, allowing inclusion of HTML authored by third-parties in web applications while protecting against XSS. Rated high severity (CVSS 8.6), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

Technical Context

This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. OWASP Java HTML Sanitizer is a configureable HTML Sanitizer written in Java, allowing inclusion of HTML authored by third-parties in web applications while protecting against XSS. In version 20240325.1, OWASP java html sanitizer is vulnerable to XSS if HtmlPolicyBuilder allows noscript and style tags with allowTextIn inside the style tag. This could lead to XSS if the payload is crafted in such a way that it does not sanitise the CSS and allows tags which is not mentioned in HTML policy. At time of publication no known patch is available. Affected products include: Owasp Java Html Sanitizer. Version information: version 20240325.1.

Affected Products

Owasp Java Html Sanitizer.

Remediation

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +0.0

CVSS: +43

POC: +20

Vendor Status

CVE-2025-66021 vulnerability details – vuln.today

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CVE-2025-66021

CVSS Vector

Lifecycle Timeline

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Analysis

Technical Context

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CVE-2025-66021

CVSS Vector

Lifecycle Timeline

Tags

Description

Analysis

Technical Context

Affected Products

Remediation

Priority Score

Vendor Status

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External POC / Exploit Code