XWiki Platform is a generic wiki platform. A vulnerability in versions from 5.0 to 16.7.1 affects users with Message Stream enabled and a wiki configured as closed from 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. This issue will not be patched as Message Stream has been deprecated in XWiki 16.8.0RC1 and is not maintained anymore. A workaround for this issue involves keeping Message Stream disabled by default. Its advised to keep it disabled from Administration > Social > Message Stream.
The product exposes a resource to the wrong control sphere, providing unintended actors with inappropriate access to the resource.
Resources such as files and directories may be inadvertently exposed through mechanisms such as insecure permissions, or when a program accidentally operates on the wrong object. For example, a program may intend that private files can only be provided to a specific user. This effectively defines a control sphere that is intended to prevent attackers from accessing these private files. If the file permissions are insecure, then parties other than the user will be able to access those files. A separate control sphere might effectively require that the user can only access the private files, but not any other files on the system. If the program does not ensure that the user is only requesting private files, then the user might be able to access other files on the system. In either case, the end result is that a resource has been exposed to the wrong party.