STCAPP (aka the SCCP telephony control application) on Cisco IOS before 15.0(1)XA1 does not properly handle multiple calls to a shared line, which allows remote attackers to cause a denial of service (port hang) by simultaneously ending two calls that were controlled by CallManager Express (CME), aka Bug ID CSCtd42552.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.