14 DAY TRIAL // Mojang released a security patch late last week, which was supposed to fix some issues reported by players. There was a vulnerability that would allow players to remotely crash servers, which was discovered and reported by a programmer.
This was patched in Minecraft 1.8.4, but that wasn't enough since more problems needed to be addressed and Mojang was quick to deliver.
Patch 1.8.5 brought more notable fixes and improvements, including better server validation for movement packets. The previous update also addressed an issue with Phantom Custom Player in Scoreboard / UUIDs of non-player entities on scoreboard that got truncated after relog.
Certain attribute values that weren't bound have been fixed as well, along with the invalid beacon effects that weren't validated.
Today's patch doesn't bring so many fixes. In fact, the only notable fix refers to an exploit with signs and command block. This was mentioned in the previous patch as well, but it looks like Mojang didn't get it right the first time.
According to developers, this version is fully compatible with all previous 1.8 versions, so it's highly recommended to update to 1.8.6 as soon as possible. Keep in mind that patch 1.8.6 is available for download in your launcher.