iOS 4.3.3 is the only version of iOS 4 that can be jailbroken on the iPad 2 tablet and all thanks to comex who managed to discover and develop a vulnerability that led to the release of an untethered jailbreak solution. Unfortunately, just a few days after the release of Comex's solution, iOS 4.3.4 appeared, which blocked that vulnerability forever and with it went the possibility of jailbreaking the iPad 2. Apple found out about the vulnerability even before the official release of jailbreakme.com 3.0 due to a "leak" that led to the publication of a part of the jailbreak solution on the Internet.
In iOS 4.3.4 Apple blocked the vulnerability known as code name CVE-2011-0226 but on the official page where he explains what's new in iOS 4.3.4, he specifies that this vulnerability was discovered by comex. I could be wrong, but I think this is the first time that Apple officially recognizes that a vulnerability in iOS was discovered by a hacker who makes jailbreak solutions.
CoreGraphics
Available for: iOS 3.0 through 4.3.3 for iPhone 3GS and iPhone 4 (GSM model), iOS 3.1 through 4.3.3 for iPod touch (3rd generation) and later, iOS 3.2 through 4.3.3 for iPad
Impact: Viewing a maliciously crafted PDF file may lead to an unexpected application termination or arbitrary code execution
Description: A signedness issue exists in FreeType's handling of Type 1 fonts. Viewing a maliciously crafted PDF file may lead to an unexpected application termination or arbitrary code execution.
CVE-ID
CVE-2011-0226: comex
