It is time to say goodbye to ASA 5500-X series hardware appliances. After making 6.2.3 the last supported Firepower Threat Defense software release for ASA 5506-X, Cisco announced that Firepower 6.6 will be last major software release for existing ASA 5500-X hardware.
It comes at no surprise that support for new software releases is ending, as all ASA 5500-X appliances are slowly approaching their End-of-Life with 2026 being the last year in which hardware support will be available for this battle tested series of Firewall appliances.
To check what the last supported software release will be on your ASA firewall check the following table:
Looking for ASA 5508-X or 5516-X? Those two are the only remaining hardware platforms that have yet to see a last supported software release. FTD 6.7.0 still supports ASA 5508/5516-X, but with the recent End-of-Sale announcement I think either 6.7.0 or the upcoming 7.0.0 software release will be the last supported major releases.