Apple has rolled-out a minor iOS 4 update to fix a potentially dangerous security flaw.

The iOS 4.3.4 upgrade plugs a vulnerability in the PDF reader in the Safari browser, which JailbreakMe.com exploited to enable users to jailbreak their device.

However, the security flaw also made iPhone, iPad and iPod users vulnerable to attackers seeking to steal personal data.

"The Jailbreakme.com exploit downloads a payload to jailbreak the phone, but it could be changed to deliver a malicious payload," Apple security expert Charlie Miller told CNET this week.

Vulnerability

The iTunes software download screen explains to users that the 4.3.4 upgrade "Fixes security vulnerability associated with viewing malicious PDF files."

This isn't the first time Apple has had to plug a security weakness relating to the PDF reader.

Back in August, JailbreakMe.com exploited another loophole to allow users to install third-party apps on their devices.