Internet Key Exchange (IKE) version 1 protocol, as implemented on Cisco IOS, VPN 3000 Concentrators, and PIX firewalls, allows remote attackers to cause a denial of service (resource exhaustion) via a flood of IKE Phase-1 packets that exceed the session expiration rate. NOTE: it has been argued that this is due to a design weakness of the IKE version 1 protocol, in which case other vendors and implementations would also be affected.

Cisco VPN 3000 series concentrators running software 4.7.0 through 4.7.2.A allow remote attackers to cause a denial of service (device reload or user disconnect) via a crafted HTTP packet.