Cisco released two security advisories yesterday. This first is regarding multiple vulnerabilities in their ASA 5500 series adaptive security appliances that can result in Denial of Service attacks. This appliance offers firewall, intrusion prevention system, anti-X and VPN services. There are workarounds for some of the vulnerabilities.
There is another advisory regarding the firewall module for the Catalyst 6500 switches and the 7600 series routers.
If you're using any of these products on your network, be sure to check out the advisories for the workarounds and fixes.