Cisco warns of firewall flaw in its Catalyst switches, 7600 Series routers

Cisco is warning that a flaw in its Firewall Services Module could result in a reload of the module, or if exploited repeatedly, could result in a sustained denial-of-service attack.

FWSM is an integrated firewall module for Cisco Catalyst 6500 switches and Cisco 7600 Series routers. 

In its security alert issued Wednesday, Cisco says there are "no known instances of intentional exploitation of this issue," but that it has "observed data streams that appear to be unintentionally triggering this vulnerability."

According to the security advisory, the security hole could be "triggered with standard network traffic, which is passed through the Application Layer Protocol Inspection process."

The only FWSM release affected by this vulnerability is FWSM System Software version 3.2(3).

FWSM software version 3.2(4) contains the fixes for the vulnerability and will be available for download the week beginning Dec. 31 at this URL.

A workaround for this vulnerability can be found at the security advisory.