Impact

The PlantUML Macro is vulnerable to Server-Side Request Forgery (SSRF). The macro allows users to specify an alternative PlantUML server via the server parameter. However, the application does not validate the supplied URL. An attacker can supply an internal IP address or a malicious external URL. The XWiki server will attempt to connect to this URL to "render" the diagram.

This issue affects all versions of the Plant UML Macro extension till version 2.4 included.

Patches

Version 2.4.1 of the Plant UML Macro extension fixes the issue by verifying if the supplied server domain matches one of the trusted domain configured inside of XWiki.

Workarounds

Protect the XWiki server by placing it in a DMZ so that it cannot access any other internal servers.

Resources

The issue was fixed in PLANTUML-25 by the commit c8b19bda93058794e04c8862fc7ca85c59b5fe5c.

For more information

If there are any questions or comments about this advisory: Open an issue in JIRA XWiki.org Send an email to Security Mailing List

Attribution

The issue was reported by Łukasz Rybak.