How to fix the Dirty COW vulnerability on Raspberry Pi
Dirty COW is a privilege escalation vulnerability found in the Linux kernel. Although it’s been there for nine years, it’s only recently been identified.
The vulnerability, which affects the 'copy-on-write' (COW) mechanism, can be found in most Linux distros, and since the Raspberry Pi runs Linux, it too is at risk.
Fortunately, the bug has been patched, and you can get it now.
If you’re running Raspbian Jessie, open up a terminal window and type:
sudo apt-get update
sudo apt-get install raspberrypi-kernel
As soon as the install is complete, reboot your Raspberry Pi and you’ll no longer be at risk.