On February 10, 2016, Cisco released CVE 2016-1287/ CWE-119. This security advisory relates to an issue contained within IKEv1 and IKEv2, which is also known as ISAKMP when configuring IPSec VPN tunnels on the ASA firewall.
This is a substantial security threat and MUST be remediated immediately. All versions of 5500 ASA's and all code lines are affected. You are truly ONLY susceptible if you are using IKEv1/2 on your firewall.