4/18/2005 -- Cisco Systems Inc. last week confirmed that its IOS-powered routers and switches were vulnerable to ICMP denial-of-service attacks.

Cisco’s warning, disseminated by means of the familiar security bulletin warning system, was the company’s third such advisory in the space of a week. The new ICMP vulnerability affects all IOS versions, but it particularly impacts IOS-powered devices that have the Path Maximum Transmission Unit Discovery enabled.

In addition to the usual suspects—Cisco’s routers and Catalyst series switches—other affected products include Cisco’s Aironet WLAN access points and bridges, the next-gen CRS-1, and Cisco’s PIX Security Appliance.

Cisco acquired Airespace—a leading provider of wireless networking solutions for enterprise customers—earlier this year. And CRS-1, which shipped last year, boasts an entirely new (next-gen) version of IOS.

It hasn’t been a good fortnight for IOS. Almost two weeks ago, Cisco admitted that attackers could exploit vulnerabilities in certain versions of IOS to gain unauthorized access to network resources. Similarly, Cisco issued another security advisory—on the same day, even—which copped to another DoS vulnerability in certain versions of IOS. As usual, Cisco released software fixes for both issues, and also published workarounds. -Stephen Swoyer