Apple has pushed out iOS 4.3.4 to fix a vulnerability in the iPhone operating system that affects the way the device handles PDF files. That PDF bug is the same one that was used by the Jailbreakme.com site to enable users to jailbreak their iPhones. Apple said last week that it would patch the PDF vulnerability, but did not disclose a timeline for doing so. The new version of iOS began showing up for download in iTunes on Friday, the update release notes say the PDF fix includes the fix, but doesn t specify other security fixes.
Source: https://threatpost.com/apple-fixes-jailbreak-pdf-bug-ios-434-071511/75439/