Cisco has identified a vulnerability that could allow an unauthenticated remote attacker to cause a denial-of-service condition. The vulnerability is due to improper processing of malformed IPv6 packets carrying extension headers. A Cisco Carrier Routing System 3 (CRS-3) running a version of Cisco IOS XR software prior to 4.2.1 is affected by this vulnerability.
Users and administrators are encouraged to review the Cisco Security Advisory and apply the necessary updates.