I saw that on the site of MEIZU Flyme OS version 3.7.9A
I just do not know with this international version (HK) or CN
The latest stable for HK is 3.5.3 which HR has linked above.
The 3.7.9A is a beta version with android 4.4.4 kitkat and a few added features but is only released as CN version as yet. However you can install any CN firmware on your HK mx3.
So latest stable is 3.5.3
Latest experimental is 3.7.9A (mind you there is a major bug where google play services and apps don’t work directly - HR has posted instructions on how to fix it which are pretty easy to follow)
If you do decide to jump from HK to CN then don’t forget to backup data and select clear data during upgrade cos otherwise you might end up im a boot loop.