A new software update for Apple Inc.'s iPhone and related devices fixes a security hole, but not all users may want the update.

The security fix addresses an issue with reading PDF files in MobileSafari, the Web browser used by the iPhone, iPad and iPod Touch, MacWorld reported July 15. The security flaws could allow an attacker "to execute malicious code" and "could allow code to inadvertently gain system privileges by posing as the user," the article said.

However, the flaws "were also being used in the latest jailbreak method for iOS devices," the article said. Many users choose to jailbreak their phones to run software beyond what Apple approves. The jailbreaking process also allows users to switch on some features that are normally locked up. "Apple's patch reportedly now disables that method," the article said.