Apple released tvOS 11.1 on Tuesday. The release keeps Apple TV up with the OS Joneses, in time with the release of iOS 11.1, macOS High Sierra 10.13.1, and watchOS 4.1.
The update notes mention no new features, but the security patch notes list fixes for issues with CoreText, Kernel, StreamingZip, WebKit, and the KRACK Wi-Fi vulnerability. All told, some 17 security issues were patched in the release.
tvOS 11.1 is available on Apple TV 4th ad 5th generation. It can be found in Settings > System > Software Updates.