The DAV component in Chandler Server (Cosmo) before 0.10.1 does not check resource creation permissions, which allows remote authenticated users to create arbitrary resources in another user's home collection.
https://bugzilla.osafoundation.org/show_bug.cgi?id=11587
http://www.vupen.com/english/advisories/2007/4214
http://lists.osafoundation.org/pipermail/cosmo-dev/2007-December/005442.html