: An attacker tricking a system or script into parsing a malicious file name could leak internal memory structures. CVE-2019-9637 Core file processing
Despite reaching its official End of Life (EOL) years ago, many legacy systems and enterprise web applications still run PHP 5.6.40. Recent security assessments and automated penetration tests frequently flag this version because multiple severe vulnerabilities have been publicly verified.
The only permanent fix for PHP 5.6 vulnerabilities is to upgrade to a currently supported version of PHP. Upgrading from 5.6 to a modern version (such as PHP 8.1, 8.2, or 8.3) is a massive jump that will likely require refactoring deprecated code.
The following verified vulnerabilities were addressed in the PHP 5.6.40 release to encourage users to upgrade from previous 5.6.x versions:
You can use this for an internal security report, a system admin log, or a client advisory. php version 5640 vulnerabilities verified
Because PHP 5.6.40 is no longer actively monitored by the community, many vulnerabilities discovered in newer versions (like PHP 7.x or 8.x) are never back-tested against 5.6.40. There is a high probability that modern exploits targeting memory management or input validation also affect PHP 5.6.40, but they remain "unverified" simply because the version is obsolete. Unsupported Branches - PHP
one, meaning any flaw discovered after its release remains unpatched unless handled by third-party maintainers (like
If your business logic completely prevents an immediate upgrade, you must source patches from third-party vendors who provide extended commercial support for EOL software.
What or hosting platform is currently running this PHP version? : An attacker tricking a system or script
For more information on PHP version 5.6.40 and the verified vulnerabilities, check out the following resources:
Upgrading to PHP version 7.x requires careful planning and testing. Consult the PHP documentation and seek professional help if needed.
The bundled OpenSSL bindings fail to support modern, secure TLS configurations by default.
To truly understand the vulnerability of PHP 5.6.40, it helps to contextualize its timeline. PHP 5.6 officially reached its on December 31, 2018. The only permanent fix for PHP 5
Older PHP versions often rely on server configuration (like open_basedir ) to mitigate path traversal. Core engine improvements in newer versions provide stronger isolation.
A "Use After Free" vulnerability where invalid input to xmlrpc_decode() could cause memory corruption or information disclosure.
Vulnerabilities in PHP's core handling of memory allocation can lead to system crashes or memory corruption.
PHP 5.6.40, released in January 2019, is the final security release of the PHP 5.6 branch
PHP 5.6.40 often interacts with outdated web components. For instance, the PHPGurukul Online Shopping Portal 2.1 (running on older PHP versions) was recently flagged for a critical SQL injection flaw ( CVE-2026-5640 ) in April 2026. Why You Must Upgrade