The immediate update of PHP 5.3.9 had been officially released. The new release focuses on improving stability of the PHP 5.3.x branch which fixed more than 90 bugs. Some of them are security related bug fixes. All users are strongly encouraged to upgrade to PHP 5.3.9.

According to the release announcement, here are the list key features and enhancements available in the PHP 5.3.9:

• Added max_input_vars directive to prevent attacks based on hash collisions. (CVE-2011-4885)
• Fixed bug #60150 (Integer overflow during the parsing of invalid exif header). (CVE-2011-4566)
• Fixed bug #55475 (is_a() triggers autoloader, new optional 3rd argument to is_a and is_subclass_of).
• Fixed bug #55609 (mysqlnd cannot be built shared)
• Many changes to the FPM SAPI module

For more details about the changes can be found in the Changelog. You can download the source file from the PHP download page.