Subversion Project reports:
svnserve takes a --pid-file option which creates a file containing the process id it is running as. It does not take steps to ensure that the file it has been directed at is not a symlink. If the pid file is in a directory writeable by unprivileged users, the destination could be replaced by a symlink allowing for privilege escalation. svnserve does not create a pid file by default. All versions are only vulnerable when the --pid-file=ARG option is used.