This vulnerability affects products running a vulnerable release of Cisco IOS Software. Devices running vulnerable products are affected if the following two conditions are verified. The show version command in the command-line interface (CLI) identifies a Cisco product that is running the vulnerable version of the software. Some Cisco devices do not support this command or may provide different output. For information about which Cisco. IOS and IOS XE Software releases are vulnerable, see the Fixed Software section of this advisory. To verify whether IKEv1 fragmentation is enabled, use the command and verify it returns output.”]
Source: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160928-ios-ikev1