wpa_supplicant 0.4.0 through 2.5 does not reject \n and \r characters in passphrase parameters, which allows local users to trigger arbitrary library loading and consequently gain privileges, or cause a denial of service (daemon outage), via a crafted (1) SET, (2) SET_CRED, or (3) SET_NETWORK command.
http://www.ubuntu.com/usn/USN-3455-1