Apple has released an upate to its iOS which fixes theÂ Â lock-screen security flaw that could allow someone to bypass the passcode at theÂ Â lock-screen and access the Phone app. In addition to the security flaw fix, this update also brings Improvements to Maps in Japan along with some other improvements and bug fixes.
The lock screen security flaw was discovered in mid February even before the release of iOS 6.1.2. But the update ofÂ iOS 6.1.2 was pushed to fix an email sync problem leaving aside this security flaw unattended.
But if you have jailbroken your Apple iOS device using the Evasi0n Jailbreaking tool, whether its a iPhone, iPad or iPod touch then you must stay away from this update. As pointed out by @musclenerd that there’s no coming back to 6.1.2 Jailbreak even if you saved blobs (except iPhone4 and ipt4g).
IOS 6.1.3 is out. Jailbreakers stay away! There's no coming back to 6.1.2 JB even if you saved blobs (except iPhone4 and ipt4g)
— Ⓜ MuscleNerd (@MuscleNerd) March 19, 2013
Hence, if you want to keep your device jail-broken, do not apply this iOS 6.1.3 update.