DISPUTED GNU screen 4.0.3 allows local users to unlock the screen via a CTRL-C sequence at the password prompt. NOTE: multiple third parties report inability to reproduce this issue.
A security flaw was found in the screen utility in the way it used to create one particular temporary file. An attacker could use this flaw to perform a symlink attack.
References: https://bugs.launchpad.net/ubuntu/+source/screen/+bug/315993 http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521123