A vulnerability in the Session Initiation Protocol (SIP) UDP throttling process of Cisco Unified Communications Manager (Cisco Unified CM) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.
The vulnerability is due to insufficient rate limiting protection.
An attacker could exploit this vulnerability by sending the affected device a high rate of SIP messages. An exploit could allow the attacker to cause the device to reload unexpectedly. The device and services will restart automatically.
Cisco has released fixes to resolve these vulnerabilities. Refer cisco-sa-20170419-ucm to obtain more information.
Following are links for downloading patches to fix the vulnerabilities: