GHSA-8g2j-rhfh-hq3r
CRITICALorg.xwiki.contrib.markdown:syntax-markdown-commonmark12 vulnerable to XSS via Markdown content
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
org.xwiki.contrib.markdown:syntax-markdown-commonmark12Real-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
Impact
The Markdown syntax is vulnerable to XSS through HTML. In particular, using Markdown syntax, it's possible for any user to embed Javascript code that will then be executed on the browser of any other user visiting either the document or the comment that contains it. In the instance that this code is executed by a user with admins or programming rights, this issue compromises the confidentiality, integrity and availability of the whole XWiki installation.
To reproduce, on an instance where the CommonMark Markdown Syntax 1.2 extension is installed, log in as a user without script rights. Edit a document and set its syntax to Markdown. Then , add the content <script>alert("XSS")</script> and refresh the page. If an alert appears containing "XSS", then the instance is vulnerable.
Patches
This has been patched in version 8.9 of the CommonMark Markdown Syntax 1.2 extension.
Workarounds
We're not aware of any workaround except upgrading.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.xwiki.contrib.markdown:syntax-markdown-commonmark12 | ≥ 8.2&&< 8.9 | 8.9 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.xwiki.contrib.markdown:syntax-markdown-commonmark12. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.xwiki.contrib.markdown:syntax-markdown-commonmark12 to 8.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8g2j-rhfh-hq3r 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.
How O3 protects you
O3 pinpoints whether GHSA-8g2j-rhfh-hq3r is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-8g2j-rhfh-hq3r. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-8g2j-rhfh-hq3r in your dependencies?
O3 detects GHSA-8g2j-rhfh-hq3r across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.