How can I patch Stagefright on an Elephone P6000 Pro?
If you are rooted you can do the following things.
However your status will still show as vulnerable, stagefright can't be executed. We will disable the stagefright module.

Method 1: 
Use a root explorer app and navigate to the system directory.
Open the file called "build.prop" and add the following code completely at the bottom of the file:

media.stagefright.enable-player=false
  media.stagefright.enable-meta=false
  media.stagefright.enable-scan=false
  media.stagefright.enable-http=false
  media.stagefright.enable-rtsp=false
  media.stagefright.enable-record=false

This will completely disable the stagefright module on your device.
This won't have a huge impact on your device performance. 

Method 2:
Use a build.prop editor app like this one: https://play.google.com/store/apps/details?id=com.jrummy.apps.build.prop.editor&amp;hl=en 

Choose to add a line and type:
      media.stagefright.enable-player

and type false as value. Repeat that for all stagefright modules.