updated 10:00 pm EST, Thu February 3, 2011
Uses exploit already patched in iOS 4.3
The Chronic Dev team have made available a new version of "greenpois0n," a release-candidate beta that offers untethered jailbreaking of devices running iOS 4.2.1, such as the iPad, third- and fourth-generation iPod Touch and iPhone 3GS or 4. The program can jailbreak without the need for SHSH blobs or other pre-existing hacks, and allows users to alter theme components, install alternate settings and use apps unapproved by the App Store -- a potential security risk, but one some users desire to gain extra functionality.
The file is listed as RC5 and is 5MB in size, and currently Mac only (Windows and Linux versions are "coming soon"). Maintaining the jailbroken status may require keeping the iOS device at v4.2.1, since the exploit used has already been patched for the forthcoming iOS 4.3, a third beta of which was seeded to developers on Tuesday. The arrival of the 4.3 final is likely to happen in the next week or so to accompany the public release of the CDMA iPhone on Verizon, as one of the features of iOS 4.3 is a "personal hotspot" system preference.
Some downloaders of the Greenpois0n program have reported that it fails to unpack properly, resulting in an unusable file. This could be an error on the part of hosting service CloudFlare or an incomplete or corrupted file at the source. The problem is expected to be resolved in due course.