CVE-2025-66021Public exploitNetwork attack vector

Cross-site scripting via unfiltered style text

Published Nov 26, 2025 · Updated Nov 26, 2025

Cross-site scripting in OWASP Java HTML Sanitizer 20240325.1 allows remote attackers to execute script via crafted HTML. When HtmlPolicyBuilder permits noscript and style with allowTextIn("style"), the sanitizer treats markup after style as CSS text and leaves disallowed script tags intact. Exploitation requires an application to use that policy and a user to render the sanitized output, allowing attacker-supplied script to run in the browser context.

CVSS severity8.6
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in OWASP Java HTML Sanitizer 20240325.1 allows remote attackers to execute script via crafted HTML. When HtmlPolicyBuilder permits noscript and style with allowTextIn("style"), the sanitizer treats markup after style as CSS text and leaves disallowed script tags intact. Exploitation requires an application to use that policy and a user to render the sanitized output, allowing attacker-supplied script to run in the browser context.

The record

CVE
CVE-2025-66021
Published
Nov 26, 2025
Updated
Nov 26, 2025
Vendor
OWASP ModSecurity
Product
OWASP Java HTML Sanitizer
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 26, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 26, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion== 20240325.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OWASP ModSecurity · OWASP Java HTML Sanitizerversion== 20240325.1

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
8.6GitHub, Inc.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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript/JScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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