It came as a massive shock to the tech industry when Apple publicly thanked Evasi0n, following the release of the iOS 7.1. This is due to the team of hackers, who have discovered many flaws with the iOS 7 security system.
The lapses are with Backup, the Certificate Trust Policy, Configurration Profiles, CoreCapture, Crash Reporting, dyld, FaceTime, ImageIO, IOKit HID Event, iTunes Store, Kernel, Office Viewer, Photos Backend, Profiles, Safari, Settings, SpringBoard, SpringBoard Lock Screen, the TelephonyUI Framework, USB Host, Video Driver, and WebKit.
Of course, these issues were already addressed by Evad3rs with its Evasi0n 7 jailbreak.
As for Apple, their decision to thank the hackers was actually due to their policy. Apple once revealed that whoever discovered the vulnerabilities on its products will be praised publicly.
Now that the iOS 7.1 has been massively improved on, jailbreaking is going to get much harder. Then again, Evad3rs are not threatened by this and will be looking forward to meeting the iOS 8.