The photo shows an iPhone 5c running Cydia 1.1.9 on iOS 7.1.1. While these types of images can easily be faked, Esser has released previous jailbreaks so we assume the photo is legit. He did shed some light on the vulnerability as well:
That iOS 7.1.1 jailbreak is not based on a long vulnerability chain. It uses a single beautiful kernel bug that goes from mobile to kernel.
It's unclear if Esser plans to release the jailbreak, but it's likely any release would happen after iOS 8 is available to see if the vulnerability still exists.
The last jailbreak, evasi0n, was released by the evad3rs, and supported iOS 7.0 - 7.0.6. The vulnerabilities it used were patched by Apple when iOS 7.1 was released.
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