CVE-2024-55877: XWiki allows remote code execution from account through macro descriptions and XWiki.XWikiSyntaxMacrosList

Any user with an account can perform arbitrary remote code execution by adding instances of XWiki.WikiMacroClass to any page. This compromises the confidentiality, integrity and availability of the whole XWiki installation.

To reproduce on a instance, as a connected user without script nor programming rights, go to your user profile and add an object of type XWiki.WikiMacroClass. Set “Macro Id”, “Macro Name” and “Macro Code” to any value, “Macro Visibility” to Current User and “Macro Description” to {{async}}{{groovy}}println("Hello from User macro!"){{/groovy}}{{/async}}. Save the page, then go to <host>/xwiki/bin/view/XWiki/XWikiSyntaxMacrosList. If the description of your new macro reads “Hello from User macro!”, then your instance is vulnerable.