Apple started seeding iOS 8.4 beta 3 for developers with the build number 12H4098c. You can download iOS 8.4 beta 3 on your device either if you have subscribed for iOS developer program or download iOS 8.4 beta 3 IPSW files from third party websites. The new beta version is supported on any iPhone iPad or iPod which compatible for iOS 8.
Steffan Esser who is known as i0n1c has tweeted about iOS 8.4 beta 3 jailbreak as soon as it released. He’s noted that he couldn’t jailbreak iOS 8.4 beta 3 because his internet service is not capable of download iOS 8.4 beta 3. This indirectly means that he can easily jailbreak iOS 8.4 new beta version.
I cannot jailbreak iOS 8.4 beta 3 because I have no internet capable of downloading it at the moment.
— Stefan Esser (@i0n1c) May 11, 2015
This time we can hope something very soon from i0n1c. He also sent out a tweet today that mentioning he will work for release his conceptual jailbreak Cyberelevat0r very soon. Cyberelevat0r will be capable of jailbreak iOS 8.4 definitely.
The new iOS 8.4 beta version doesn’t seem having big updates except security enhancements and bug fixes. 8.4 beta 3 update sized 142 MB and you can grab the complete update notice here.