As Cloudways reports, the stable landscape has evolved to . Staying on 5.6.40 means missing out on:
PHP 5.6.40 was released on January 10, 2019. It marked the absolute end-of-life (EOL) for the PHP 5.6 release cycle. No official security patches or updates have been issued for this version by the PHP development team since that date.
PHP End-of-Life Dates: Support Timeline for Every Version (2026)
To review specific Common Vulnerabilities and Exposures (CVE) details, CVSS severity scores, and technical breakdowns for PHP 5.6.40, utilize authoritative security databases: php version 5640 vulnerabilities link
: When PHP instantiates or destroys these objects, it triggers "magic methods" (like __wakeup() or __destruct() ), allowing attackers to execute arbitrary code on the underlying server. 2. Heap-Based Buffer Overflows
There is no official PHP version "5.6.40" in the standard PHP release history. The official versions were 5.6.39 and then 5.6.40 (Release Date: Jan 10, 2019). However, given the high likelihood of a typo, this post covers PHP 5.6.40 (the last official security release of the 5.6 branch) and also addresses the possibility you meant the 5.6.4.0 alpha build or a general search for CVE links.
Exposure of database credentials, encryption keys, environment variables, and user session data. Tracking and Verifying Vulnerability Documentation As Cloudways reports, the stable landscape has evolved to
: The National Vulnerability Database (NVD) is another resource where you can find detailed information on vulnerabilities, including those affecting PHP. You can search by keyword, vendor, product, and version.
PHP 5.6.40 relies on an inherently vulnerable version of the internal GD graphics processing architecture.
The multibyte string ( mbstring ) extension in PHP 5.6.40 suffers from a sequence of critical heap-based buffer overflows. Attackers can exploit these flaws by sending targeted regular expression inputs to applications processing multibyte characters. No official security patches or updates have been
: If an application passes user-controlled input directly into the unserialize() function, attackers can manipulate the serialized string to inject malicious PHP objects.
Because PHP 5.6.40 has been EOL for years, it has accumulated a backlog of known vulnerabilities that will never be fixed. While PHP 5.6.40 patched issues present in earlier 5.6 versions (like 5.6.30), it is vulnerable to classes of bugs discovered after January 2019.