A website that shows iPhone and iPad users how to jailbreak their devices, so they can run unauthorised apps, could help hackers exploit a vulnerability in the iOS software, says Sophos.

According to the security firm, the latest flaw in the mobile operating system can be found in the way the mobile version of Apple's web browser Safari handles PDF files. However, the jailbreaking code, which wa released by JailbreakMe, could be utilised by hackers to build malicious software that exploits the flaw within days.

"Cybercriminals would be able to create booby-trapped web pages that could - if visited by an unsuspecting iPhone, iPod Touch or iPad owner - run code on visiting devices without the user's permission," said Graham Cluley, senior technology consultant at Sophos.

"Apple will be furious that this vulnerability has been made public in this way, and that they have not yet got a patch to protect their millions of users."

Apple admitted it was aware of the flaw and was is curtrently working on a fix.

"We are developing a fix that will be available to customers in an upcoming software update," Apple spokeswoman Trudy Muller told Reuters.

"A website like JailBreakMe is making it easy to jailbreak your iPhone or iPad - but it could also be said to be giving a blueprint to malicious hackers on how to infect devices with malware," said Cluley.

"There are many cybercriminals who would love to infect iPhones and iPads, and eyes will now be turning towards Apple to see how quickly they can issue a patch for iOS to close this vulnerability."