Although 5.6.40 fixed previous flaws, subsequent research and "forever day" vulnerabilities now affect any remaining installations. Key verified issues include:
Continuing to run PHP 5.6.40 (or any 5.6 sub-version) is a significant security liability that exposes your application to known exploits. Even if you are running the patched Debian LTS versions, you are missing out on the architectural security improvements of modern PHP. php version 5640 vulnerabilities verified
This is one of the most critical vulnerabilities affecting PHP 5.6.40. It is a buffer underflow in php-fpm (the Fast Process Manager for PHP). When PHP is run in an Nginx + php-fpm environment with certain non-default configurations, a remote attacker could exploit this flaw to execute arbitrary code on the server. An exploit was released shortly after the public disclosure. Although 5
Even though 5.6.40 was the last official release before PHP 5.6’s final EOL, exist because: This is one of the most critical vulnerabilities