The IronPort Spam Quarantine (ISQ) component in the web framework in IronPort AsyncOS on Cisco Email Security Appliance devices before 7.1.5-106 and 7.3, 7.5, and 7.6 before 7.6.3-019 and Content Security Management Appliance devices before 7.9.1-102 and 8.0 before 8.0.0-404 allows remote attackers to cause a denial of service (service crash or hang) via a high rate of TCP connection attempts, aka Bug IDs CSCzv25573 and CSCzv81712.