How severe is CVE-2022-23520?

CVE-2022-23520 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2022-23520?

CVE-2022-23520 affects the following packages: rails-html-sanitizer (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2022-23520?

Update rails-html-sanitizer to 1.4.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-23520 is resolved across your whole dependency graph.

How do I detect CVE-2022-23520 in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rails-html-sanitizer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2022-23520 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2022-23520 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2022-23520, including 2 in-the-wild exploitations 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-2022-23520?

CVE-2022-23520 has an EPSS (Exploit Prediction Scoring System) score of 1.2%, placing it in the 68th 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.

What type of vulnerability is CVE-2022-23520?

CVE-2022-23520 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2022-23520 published, and has it been updated?

CVE-2022-23520 was published on December 14, 2022 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎

💎 RubyGems

Not in CISA KEV

MEDIUM severity

CVE-2022-23520 — rails-html-sanitizer

MEDIUM

CVE-2022-23520 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in rails-html-sanitizer. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for rails-html-sanitizer — see the affected versions and patch details below.

rails-html-sanitizer contains an incomplete fix for an XSS vulnerability

Also known asGHSA-rrfc-7g8p-99q8

Published

Dec 14, 2022

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

2 known

Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs68th percentile — riskier than 68% of all scored CVEsHighest risk

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

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

💎rails-html-sanitizer

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

Description

Summary

There is a possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer. This is due to an incomplete fix of CVE-2022-32209.

Versions affected: ALL
Not affected: NONE
Fixed versions: 1.4.4

Impact

A possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer may allow an attacker to inject content if the application developer has overridden the sanitizer's allowed tags to allow both "select" and "style" elements.

Code is only impacted if allowed tags are being overridden using either of the following two mechanisms:

Using the Rails configuration config.action_view.sanitized_allow_tags=:

# In config/application.rb
config.action_view.sanitized_allowed_tags = ["select", "style"]

(see https://guides.rubyonrails.org/configuring.html#configuring-action-view)

Using the class method Rails::Html::SafeListSanitizer.allowed_tags=:

# class-level option
Rails::Html::SafeListSanitizer.allowed_tags = ["select", "style"]

All users overriding the allowed tags by either of the above mechanisms to include both "select" and "style" should either upgrade or use one of the workarounds immediately.

NOTE: Code is not impacted if allowed tags are overridden using either of the following mechanisms:

the :tags option to the Action View helper method sanitize.
the :tags option to the instance method SafeListSanitizer#sanitize.

Workarounds

Remove either "select" or "style" from the overridden allowed tags.

References

Credit

This vulnerability was responsibly reported by Dominic Breuker.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`rails-html-sanitizer`	all versions	1.4.4`bundle update rails-html-sanitizer --conservative`

Affected Products

2 products · 2 configurations

debian linuxdebian

1 version

10.0

Application

rails html sanitizersrubyonrails

< 1.4.4

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.

rails-html-sanitizer is responsible for sanitizing HTML fragments in Rai…

github.comNVDDec 2022

Report on hackerone.com

hackerone.comNVDDec 2022

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rails-html-sanitizer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rails-html-sanitizer to 1.4.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-23520 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

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 Satellite 6.13 for RHEL 8	`tfm-rubygem-rails-html-sanitizer-0:1.4.4-1.el8sat`	RHSA-2023:2097

Frequently Asked Questions

## Summary There is a possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer. This is due to an incomplete fix of CVE-2022-32209. - Versions affected: ALL - Not affected: NONE - Fixed versions: 1.4.4 ## Impact A possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer may allow an attacker to inject content if the application developer has overridden the sanitizer's allowed tags to allow both "select" and "style" elements. Code is only impacted if allowed tags are being overridden using either of the following two mechanisms: 1. Using th