svn-workbench 1.6.2 and earlier on a system with xeyes installed allows local users to execute arbitrary commands by using the "Command Shell" menu item while in the directory trunk/$(xeyes).
https://bugzilla.redhat.com/show_bug.cgi?id=1262928
https://bugs.launchpad.net/ubuntu/+source/svn-workbench/+bug/1495268