Firmware update 7.6.9 improves the security of your base station and is recommended for all Apple 802.11n Wi-Fi base stations including AirPort Express, AirPort Extreme and AirPort Time Capsule.
Firmware update 7.7.9 improves the security of your base station and is recommended for all AirPort Extreme and AirPort Time Capsule base stations with 802.11ac.
For more information on the security content of these updates see: http://support.apple.com/kb/HT1222
For more information on using AirPort products, go to the Product Support Page at: http://www.apple.com/support/airport
For detailed information on AirPort base station firmware updates, including instructions how to install the update, please visit: http://support.apple.com/kb/HT20159