The evad3rs on Friday released an updated evasi0n7 jailbreak utility. It is still impossible to jailbreak iPhone 5, 5c and 5s running iOS 7.1, however, evasi0n7 1.0.8 brings support for iOS 7.0 build 11A466.
11A466 is probably a factory build, which means it is not available for download. This iOS 7 version is installed primarily on new devices. For instance, one user says that iPhone 5s, which he got from Apple as a replacement for his damaged smartphone, is currently running iOS 7 build 11A466. He adds that he can’t jailbreak his new device.
As noted by
At some point during the past week or so, the evad3rs released an update for evasi0n7, bringing the jailbreak tool to version 1.0.8. According to the change log, the software now supports build 11A466 of iOS 7.