System Security Services Daemon (SSSD) before 1.0.1, when the krb5 auth_provider is configured but the KDC is unreachable, allows physically proximate attackers to authenticate, via an arbitrary password, to the screen-locking program on a workstation that has any user's Kerberos ticket-granting ticket (TGT); and might allow remote attackers to bypass intended access restrictions via vectors involving an arbitrary password in conjunction with a valid TGT.