slock allows attackers to bypass the screen lock via vectors involving an invalid password hash, which triggers a NULL pointer dereference and crash.
http://www.securityfocus.com/bid/92546
http://www.openwall.com/lists/oss-security/2016/08/18/24
http://www.openwall.com/lists/oss-security/2016/08/18/22
http://s1m0n.dft-labs.eu/files/slock/slock.txt
http://git.suckless.org/slock/commit/?id=d8bec0f6fdc8a246d78cb488a0068954b46fcb29