Following the release of the first iOS 9.3.2 and watchOS 2.2.1 betas, Apple has also pushed out the first build of OS X El Capitan 10.11.5 to developers for testing. The build carriers the number of 15F18b and is available for download from the “Updates” tab in the Mac App Store as long as your Mac is registered to receive developer betas.
Dot-dot updates tend to be mainly focused on bug fixes, so don’t expect to see any user facing changes made to OS X in this build. There also doesn’t appear to be any release notes, so we’re really flying blind on this one.
We’ll update this post if anything new is discovered in OS X 10.11.5!