CVE-2015-6321

CVE-2015-6321 is a denial-of-service vulnerability affecting Cisco Email Security Appliance (ESA), Content Security Management Appliance (SMA), and Web Security Appliance (WSA) devices running specific AsyncOS versions. An unauthenticated remote attacker can exploit this by sending a flood of TCP packets, leading to excessive memory consumption and device unavailability. With a CVSS score of 7.8 (High), this vulnerability is easily exploitable over the network with low attack complexity, resulting in a complete loss of availability. There is no evidence of active exploitation, public exploit code, or significant community discussion, though it did receive some media coverage at the time of disclosure.