Heise Security is reporting of a DoS vulnerability in Cisco IOS that can be exploited to reboot ISP routers.
The problem arises when processing the “show ip bgp regexp” command if certain regular expressions are used as arguments. As a result, the router reboots and has to rebuild its BGP routing table. If this occurs several times in succession, resulting in a route becoming unavailable repeatedly, the router may be ignored by other providers for a certain amount of time as a result. This would cause a provider’s network to become unavailable.
Heise reports that Cisco has yet to release details of or fixes to this problem. Heise says some ISPs have implemented their own workarounds.
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