The PHP development group has officially released the latest version of the language in the 5.5.x series - PHP 5.5.12:

The PHP Development Team announces the immediate availability of PHP 5.5.12. This release fixes several bugs against PHP 5.5.11, as well as CVE-2014-0185 regarding PHP-FPM. All PHP users are encouraged to upgrade to this new version.

Among the bugs fixed in this release are things around cURL support, DateTime functionality, Fileinfo and Json handling. The PHP-FPM issue (CVE-2014-0185) relates to a possible issue in the FPM functionality that would allow for possible privilege escalation due to insecure default configuration. It is highly recommended that PHP-FPM users update to this latest version immediately. As always you can download this latest version from the main download page or for Windows users, windows.php.net.