Following on the heels of the other latest releases of PHP (5.5.22 and 5.4.38), the PHP development group has release the latest in the 5.6.x series - PHP 5.6.6.
The PHP development team announces the immediate availability of PHP 5.6.6. This release fixes several bugs and addresses CVE-2015-0235 and CVE-2015-0273. All PHP 5.6 users are encouraged to upgrade to this version.
You can get this latest release either directly from the downloads page (well, from a mirror) or if you're a Windows user you can get the binaries here. Upgrading is definitely recommended and you can find all the details of the release and what what fixed in the Changelog.