Summary
=======
Recent versions of Cisco IOS Software support RFC4893 ("BGP Support
for Four-octet AS Number Space") and contain two remote denial of
service (DoS) vulnerabilities when handling specific Border Gateway
Protocol (BGP) updates.
These vulnerabilities affect only devices running Cisco IOS Software
with support for four-octet AS number space (here after referred to as
Software" at the following link:
http://www.cisco.com/en/US/prod/collateral/iosswrel/ps8803/ps5845/product_bulletin_c25-478699.html
BGP is configured in Cisco IOS XR software with the configuration
command router bgp [AS Number] or router bgp [X.Y]. The device is
vulnerable if it is running affected Cisco IOS XR version and has BGP
configured.
The following example shows a Cisco IOS XR software device configured
with BGP:
