Apple released Time Capsule and AirPort Base Station (802.11n) Firmware 7.4.1 late on Thursday. The update addressed security-related issues the could lead to a denial of service attack, an unexpected device shutdown, or allow someone to observe private network traffic.
The firmware update corrects problems with out-of-bounds memory access when handling PPPoE discovery packets, along with IPv6 and IPv6 Neighbor Discovery. Apple is also recommending users install AirPort Utility 5.4.1 before installing the firmware update.
Time Capsule and AirPort Base Station (802.11n) Firmware 7.4.1 is free and can be installed via AirPort Utility.