CVE-2025-32783: Unregistered users can see "public" messages from a closed wiki via notifications from a different wiki

This vulnerability impacts users of a subwiki of XWiki where Message Stream is enabled and use, if they configured their wiki to be closed by selecting “Prevent unregistered users to view pages” in the Administrations Rights.

The vulnerability is that any message sent in a subwiki to “everyone” is actually sent to the farm: any visitor of the main wiki will be able to see that message through the Dashboard, even if the subwiki is configured to be private.