UNIVERGE Aspire series PBX (UNIVERGE Aspire WX from 1.00 to 3.51, UNIVERGE Aspire UX from 1.00 to 9.70, UNIVERGE SV9100 from 1.00 to 10.70, and SL2100 from 1.00 to 3.00) allows a remote authenticated attacker to cause system down and a denial of service (DoS) condition by sending a specially crafted command.