Quake 1 and NetQuake servers allow remote attackers to cause a denial of service (resource exhaustion or forced disconnection) via a flood of spoofed UDP connection packets, which exceeds the server's player limit.

Quake 1 (quake1) and ProQuake 1.01 and earlier allow remote attackers to cause a denial of service via a malformed (empty) UDP packet.

Buffer overflows in Quake 1.9 client allows remote malicious servers to execute arbitrary commands via long (1) precache paths, (2) server name, (3) server address, or (4) argument to the map console command.