forticlientsslvpn suffers from an insecure lock file creation issue.
Upon starting the forticlientsslvpn, the file 'forticlientsslvpn.lock'
is created under the /tmp directory with octal permissions
0666. 

The client does not first check if this file exists, or if it is even
currently owned by the user running the client.

P.O.C
Create a symlink from /tmp/forticlientsslvpn.lock
to /some/file/owned_by_root as a non-root user. Then run the
forticlientsslvpn client as root and the file you pointed at will then
be overwritten upon execution.