XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. It’s possible to make XWiki create many new schemas and fill them with tables just by using a crafted user identifier in the login form. This may lead to degraded database performance. The problem has been patched in XWiki 13.10.8, 14.6RC1 and 14.4.2. Users are advised to upgrade. There are no known workarounds for this issue.