Cisco IOS XR, when configured for Multi Protocol Label Switching (MPLS) and running on Cisco CRS-1 routers, allows remote attackers to cause a denial of service (Modular Services Cards (MSC) crash or "MPLS packet handling problems") via certain MPLS packets, as identified by Cisco bug IDs (1) CSCsd15970 and (2) CSCsd55531.
Cisco IOS 12.0 through 12.4 and IOS XR before 3.2, with IPv6 enabled, allows remote attackers on a local network segment to cause a denial of service (device reload) and possibly execute arbitrary code via a crafted IPv6 packet.