The PHP development team announces the immediate availability of PHP 5.5.21. This release fixes several bugs as well as CVE-2015-0231, CVE-2014-9427 and CVE-2015-0232. All PHP 5.5 users are encouraged to upgrade to this version.
For source downloads of PHP 5.5.21 please visit our downloads page, Windows binaries can be found on windows.php.net/download/. The list of changes is recorded in the ChangeLog.