A flaw was found in the way spice-client processed certain messages sent from the server. An attacker, having control of malicious spice-server, could use this flaw to crash the client or execute arbitrary code with permissions of the user running the client. spice-gtk versions through 0.34 are believed to be vulnerable.
spice-gtk 0.14, and possibly other versions, invokes the polkit authority using the insecure polkit_unix_process_new API function, which allows local users to bypass intended access restrictions by leveraging a PolkitUnixProcess PolkitSubject race condition via a (1) setuid process or (2) pkexec process, a related issue to CVE-2013-4288.