Critical

org.xwiki.contrib.markdown:syntax-markdown-commonmark12 vulnerable to XSS via Markdown content

  • Disclosed: 30.04.2025
  • Updated: 11.10.2026 12:21

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 software

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PlatformPackageVulnerable versionsFixed in
Java / Kotlin (Maven) org.xwiki.contrib.markdown:syntax-markdown-commonmark12 >= 8.2, < 8.9 8.9

References

CVSS score 9/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Weakness (CWE)
CWE-79
Platform
Java / Kotlin (Maven)
Package
org.xwiki.contrib.markdown:syntax-markdown-commonmark12
Disclosed
30.04.2025
Updated
11.10.2026 12:21

Sources and licenses

OSV / GitHub Advisory Database - GHSA-8g2j-rhfh-hq3r - CC BY 4.0

Vulnerability history: org.xwiki.contrib.markdown:syntax-markdown-commonmark12

All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.

This is the only known vulnerability of this package.

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