This important update also fixes a handful of lock screen bypass vulnerabilities. These vulnerabilities were present in the latest iOS i.e. iOS 6 right from the time of its release. This vulnerability gave access stored contacts and photographs to anyone who had access to your phone by bypassing the lock screen. The intruder could also make calls after bypassing the lock screen.
Apple has highly recommended everyone to download and install the latest iOS with the exception of the jailbreakers as the update would remove the evasi0n jailbreak and as of today no jailbreaking technique has been released for the latest iOS update. Furthermore, it is still not clear when a jailbreak for iOS 6.1.3 would come out if any.
Earlier in March, prominent iOS hacker Charlie Miller expressed his views on the jailbreaking culture and opined that the last evasi0n jailbreak might just be the last one the world will ever see and reasoned his statement with 5 probable reasons. Lack of enthusiasm among users was cited as one of the reasons.