A vulnerability in the implementation of the virtual fragmentation reassembly (VFR) feature for IP version 6 (IPv6) in Cisco IOS Software could allow an unauthenticated, remote attacker to cause an affected device to hang or reload, resulting in a denial of service (DoS) condition.
The vulnerability is due to a race condition while accessing the reassembly queue for IPv6 fragments. An attacker could exploit this vulnerability by sending a crafted stream of valid IPv6 fragments. Repeated exploitation may result in a sustained DoS condition.
Cisco has released free software updates that address this vulnerability. There are no workarounds for this vulnerability.