CallManager Express (CME) on Cisco IOS before 15.0(1)XA allows remote authenticated users to cause a denial of service (device crash) by using an extension mobility (EM) phone to interact with the menu for SNR number changes, aka Bug ID CSCta63555.
https://exchange.xforce.ibmcloud.com/vulnerabilities/64681
http://www.securityfocus.com/bid/45765
http://www.cisco.com/en/US/docs/ios/15_0/15_0x/15_01_XA/rn800xa.pdf