The AcquireDaemonLock function in ipcdUnix.cpp in Sun Innotek VirtualBox before 2.0.6 allows local users to overwrite arbitrary files via a symlink attack on a /tmp/.vbox-$USER-ipc/lock temporary file.
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.