Apple has finally fixed an "unpatched" bug in the latest iOS update that had left its most up-to-date iPhones vulnerable to hacking risk. The new update "iOS 12.4.1" introduces a fix for vulnerability in which, according to Apple, "a malicious application may be able to execute arbitrary code with system privileges".

"We would like to acknowledge @Pwn20wnd for their assistance," said Apple.

A security researcher who goes by the name of "Pwn20wnd" published a jailbreak for the earlier iOS 12.4 update.

Apple reportedly unpatched a bug in the latest iOS update 12.4 that it had fixed in the earlier iOS 12.3 update - leaving its devices vulnerable to cybercriminals.

Jailbreaking an iPhone lets people customise their iOS devices and run unsupported apps. Apple never allows unsupported apps on its iOS platform, which makes its devices extra secure.

As a result of the unpatched bug, all iPhones running iOS 12.4 could be jailbroken.

Several iPhone users tweeted that they were successfully running the "jailbreak".

Apple recently announced to pay up to $1 million (roughly Rs. 7.2 crores) to security researchers for finding flaws and vulnerabilities as part of its bug bounty programme.

The announcement was made by Ivan Krstic, Head of security engineering and architecture at Apple, during the annual Black Hat security conference in Las Vegas.