The HTTP server in Cisco IOS on Catalyst switches does not properly handle TCP socket events, which allows remote attackers to cause a denial of service (device crash) via crafted packets on TCP port (1) 80 or (2) 443, aka Bug ID CSCuc53853.
Cisco IOS 15.0 and 15.1 on Catalyst 3560 and 3750 series switches allows remote authenticated users to cause a denial of service (device reload) by completing local web authentication quickly, aka Bug ID CSCts88664.