UPDATE 8/30/19 - Apple has released iOS 12.4.1 which fixes the vulnerability.
Original Story -
Looks like hackers can dust off their jailbreaking skills as a vulnerability was discovered in iOS 12.4. According to Vice, iOS 12.4, the latest version, reintroduced a bug that was fixed in iOS 12.3. Several iPhone users took to Twitter, claiming they used the Pwn20wnd jailbreak on their phones. Unfortunately, the bug also makes it easier to hack iPhones. So, until iOS 12.4.1 comes out, many iPhones are at risk.