The risk posed by a serious DoS vulnerability to a wide range of Cisco Systems routers and switches has been upgraded following the release of an exploit onto a full disclosure mailing list.

As we reported yesterday, The DoS vulnerability arises from a bug in Cisco's core IOS software which means vulnerable devices to stop processing inbound packets on receipt of maliciously constructed IPv4 packets. Normal service would be restored only with a manual reboot.

No alarms will be triggered, nor will the router reload to correct itself. Cisco IOS versions 11.x and 12.x prior to 12.3 are affected by the vulnerability. That means almost everybody is affected.

rest of story