Cisco IOS 15.1 and 15.2, when a clientless SSL VPN is configured, allows remote authenticated users to cause a denial of service (device reload) by using a web browser to refresh the SSL VPN portal page, as demonstrated by the Android browser, aka Bug ID CSCtr86328.
http://www.securitytracker.com/id?1027371
http://www.cisco.com/en/US/docs/ios/15_1/release/notes/151-2TCAVS.html