Cisco IOS 12.0(32)S12 through 12.0(32)S13 and 12.0(33)S3 through 12.0(33)S4, 12.0(32)SY8 through 12.0(32)SY9, 12.2(33)SXI1, 12.2XNC before 12.2(33)XNC2, 12.2XND before 12.2(33)XND1, and 12.4(24)T1; and IOS XE 2.3 through 2.3.1t and 2.4 through 2.4.0; when RFC4893 BGP routing is enabled, allows remote attackers to cause a denial of service (memory corruption and device reload) by using an RFC4271 peer to send an update with a long series of AS numbers, aka Bug ID CSCsy86021.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6697
http://www.vupen.com/english/advisories/2009/2082
http://www.securitytracker.com/id?1022619
http://www.securityfocus.com/bid/35862
http://www.cisco.com/en/US/products/products_security_advisory09186a0080aea4c9.shtml