Our subversion server is configured to use authentication - each user has username and password which (s)he uses. Each repository and directory on the server have different access rules, so that each user can see only those sources that he has authorization for. Now as collaborator is setup to use a single username/password when accessing svn, this creates a hole in the authorization scheme. Each user who has access to collaborator can use collaborator to access sources in every repository and directory collaborator has access to.
A proposed solution: Make collaborator ask for svn username and password when uploading sources from subversion.