Cross-site Scripting in in JRubyGHSA-wmq2-jc9m-xp4m
GHSA-wmq2-jc9m-xp4m is a Cross-site Scripting (XSS) vulnerability in org.jruby:jruby-core. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for org.jruby:jruby-core — see the affected versions and patch details below.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
org.jruby:jruby-coreReal-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 regular expression engine in JRuby before 1.4.1, when $KCODE is set to 'u', does not properly handle characters immediately after a UTF-8 character, which allows remote attackers to conduct cross-site scripting (XSS) attacks via a crafted string.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.jruby:jruby-core | all versions | 1.4.1org.jruby:jruby-core:1.4.1 |
Affected Products
jrubyjrubyResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jruby:jruby-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.jruby:jruby-core to 1.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wmq2-jc9m-xp4m 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.
Frequently Asked Questions
Is GHSA-wmq2-jc9m-xp4m in your dependencies?
Find it across Maven, including transitive dependencies.