From the fine folks at php.net:
(c) SANS Internet Storm Center. https://isc.sans.edu Creative Commons Attribution-Noncommercial 3.0 United States License.The PHP development team announces the immediate availability of PHP 5.5.23. Several bugs have been fixed as well as CVE-2015-0231, CVE-2015-2305 and CVE-2015-2331. All PHP 5.5 users are encouraged to upgrade to this version.