This patch provides protection against several types of security-related issues, including remote code execution, information leaks and cross-site scripting. - Added Oct 11, 2016
More information about the individual issues addressed by this patch is available in the patch details.
NOTE: if you have installed version 1 of the patch, it is recommended to do the following:
Revert SUPEE-8788 v1/
Revert SUPEE-1533 (if installed)
Install SUPEE-3941 (if not installed yet)
Install SUPEE-8788 v2
More details about the patch issues could be found here.