How severe is CVE-2021-42575?

CVE-2021-42575 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

How do I fix CVE-2021-42575?

Update com.googlecode.owasp-java-html-sanitizer:owasp-java-html-sanitizer to 20211018.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-42575 is resolved across your whole dependency graph.

How do I mitigate CVE-2021-42575 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2021-42575 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-42575, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-42575?

CVE-2021-42575 has an EPSS (Exploit Prediction Scoring System) score of 3.0%, placing it in the 87th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2021-42575 published, and has it been updated?

CVE-2021-42575 was published on October 19, 2021 and was last updated on February 19, 2024. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

CRITICAL severity

CVE-2021-42575 — owasp-java-html-sanitizer

CRITICAL

CVE-2021-42575 is a critical-severity (CVSS 9.8) vulnerability in com.googlecode.owasp-java-html-sanitizer:owasp-java-html-sanitizer. 1 public exploit reference exists, so weaponization risk is real. A fix is available for com.googlecode.owasp-java-html-sanitizer:owasp-java-html-sanitizer — see the affected versions and patch details below.

Policies not properly enforced in OWASP Java HTML Sanitizer

Published

Oct 19, 2021

Updated

Feb 19, 2024

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Oct 12, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

3.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs87th percentile — riskier than 87% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-42575 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

☕com.googlecode.owasp-java-html-sanitizer:owasp-java-html-sanitizer

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

The OWASP Java HTML Sanitizer before 20211018.1 does not properly enforce policies associated with the SELECT, STYLE, and OPTION elements.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`com.googlecode.owasp-java-html-sanitizer:owasp-java-html-sanitizer`	all versions	20211018.1`com.googlecode.owasp-java-html-sanitizer:owasp-java-html-sanitizer:20211018.1`

Affected Products

3 products · 8 configurations

Application

middleware common libraries and toolsoracle

2 versions

12.2.1.3.012.2.1.4.0

Application

primavera unifieroracle

≥ 17.7 && ≤ 17.12

4 versions

18.819.1220.1221.12

Application

java html sanitizerowasp

< 20211018.2

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

The OWASP Java HTML Sanitizer before 20211018.1 does not properly enforc…

docs.google.comNVDOct 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.googlecode.owasp-java-html-sanitizer:owasp-java-html-sanitizer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update com.googlecode.owasp-java-html-sanitizer:owasp-java-html-sanitizer to 20211018.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-42575 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Product	Fixed in	Advisory
Red Hat Single Sign-On 7.6.1	see advisory	RHSA-2022:7417
Red Hat Single Sign-On 7.6 for RHEL 7	`rh-sso7-keycloak-0:18.0.3-1.redhat_00001.1.el7sso`	RHSA-2022:7409
Red Hat Single Sign-On 7.6 for RHEL 8	`rh-sso7-keycloak-0:18.0.3-1.redhat_00001.1.el8sso`	RHSA-2022:7410
Red Hat Single Sign-On 7.6 for RHEL 9	`rh-sso7-0:1-5.el9sso`	RHSA-2022:7411

Frequently Asked Questions

The OWASP Java HTML Sanitizer before 20211018.1 does not properly enforce policies associated with the `SELECT`, `STYLE`, and `OPTION` elements.

O3 Security · Impact-Aware SCA

Is CVE-2021-42575 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

9.8/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weaponization

No known public exploit tooling found.

Timeline

Disclosed

Oct 19, 2021

First exploit

Oct 22, 2021

3 days after disclosure — rapid exploitation

Last updated

Feb 19, 2024

Identifiers

CVE-2021-42575

References

Advisorynvd.nist.gov Webdocs.google.com Weboracle.com Weboracle.com

Related vulnerabilities

This CVE is critical severity — higher than any of the other 2 CVEs affecting owasp-java-html-sanitizer (highest there: high).

CVE-2025-66021CVE-2011-4457

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedFeb 19, 2024

CVE-2021-42575 — owasp-java-html-sanitizer

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Fixing This On Your OS

Frequently Asked Questions

Is CVE-2021-42575 in your dependencies?