CVE-2014-3347

Cisco IOS 15.1(4)M2 on Cisco 1800 ISR devices, when the ISDN Basic Rate Interface is enabled, allows remote attackers to cause a denial of service (device hang) by leveraging knowledge of the ISDN phone number to trigger an interrupt timer collision during entropy collection, leading to an invalid state of the hardware encryption module, aka Bug ID CSCul77897.