Cisco Security Advisory 20160803-ucm: Cisco Unified Communications Manager IM and Presence Service SIP Packet Processing Denial of Service Vulnerability

A vulnerability in Session Initiation Protocol (SIP) processing functions of the Cisco Unified Communications Manager Instant Messaging (IM) and Presence Service could allow an unauthenticated, remote attacker to cause the Cisco SIP Proxy Daemon (sipd) process to restart unexpectedly, resulting in a denial of service (DoS) condition on a targeted system

The vulnerability is due to improper input validation of SIP packet headers. An attacker could exploit this vulnerability by sending a crafted SIP packet to a targeted system. A successful exploit could allow the attacker to cause the sipd process to restart unexpectedly, resulting in a DoS condition on the system. If the sipd process restarts repeatedly, a successful exploit could also result in a sustained DoS condition and cause high disk utilization due to a large number of sipd core files being written to disk, which could exacerbate the DoS condition.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:

For assistance with determining whether your equipment is affected, or for assistance with remediation, please contact the Symplexity support team at

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