Unpatched issues in the XML-RPC and GD libraries can be exploited to crash web applications remotely. Critical Risk Assessment Unsupported Branches - PHP
A heap-based buffer over-read in PHAR extension reading functions. php version 5640 vulnerabilities verified
PHP 5.6.40, released in January 2019, is the final security release of the PHP 5.6 branch Unpatched issues in the XML-RPC and GD libraries