You want a link to a list of flaws. But the real risk is not the list; it is the . Here is why collecting CVEs for 5.6.40 is a losing battle:
Because this version is End-of-Life (EOL), any vulnerabilities discovered after its final release remain unpatched by the official PHP development team. Core Vulnerabilities in PHP 5.6.40 php version 5640 vulnerabilities link
Do not fall into the trap of simply monitoring the "vulnerabilities link." The link is a tombstone. Every month that you serve PHP 5.6.40 to the public internet, you are betting that no attacker will click the exploit link before you click the upgrade button. You want a link to a list of flaws
Detailed lists of historical vulnerabilities and CVEs for this version can be found on CVE Details Blog Post: The Hidden Risk of PHP 5.6.40 in 2026 If you are still running PHP 5.6.40 Core Vulnerabilities in PHP 5
Staying on 5.6.40 is often referred to as "leaving your front door unlocked".
When you search for , you are effectively searching for the security report of the last known state of PHP 5.6.
A heap-based buffer over-read in the PHAR extension may allow attackers to read memory past actual data while parsing filenames.