slock 0.9 does not properly handle the XRaiseWindow event when the screen is locked, which might allow physically proximate attackers to obtain sensitive information by pressing a button, which reveals the desktop and active windows.
https://exchange.xforce.ibmcloud.com/vulnerabilities/74666
https://bugzilla.redhat.com/show_bug.cgi?id=786310
http://www.securityfocus.com/bid/52922