Apple has released iOS 9.3.5 for all compatible iPhone, iPad, and iPod touch devices.
The small update appears to include security fixes and is therefore recommended for all users

Updating to iOS 9.3.5 is easy as we’ll walk through below, and advanced users can also choose to use the IPSW firmware files to update manually with iTunes if desired.

Out of no where, Apple has made available for download iOS 9.3.5 links for supported iPhone, iPad and iPod touch devices. This release comes approximately three weeks after Apple released iOS 9.3.4 to public.

iOS 9.3.5 download IPSW links,