For a complete, real-time list of all Common Vulnerabilities and Exposures (CVEs) associated with this version, refer to these primary tracking links:
Running PHP 5.6.40 in a production environment introduces severe business and technical compliance risks:
The GD graphics processor built into PHP 5.6.40 suffers from memory management issues. php version 5640 vulnerabilities link
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Use tools to scan your codebase for deprecated functions. For a complete, real-time list of all Common
Given the severity of the risks, remaining on PHP 5.6.40 is not a sustainable strategy. Here is your path forward:
Running an EOL (End-of-Life) PHP version means your website has no protection against new security threats. Here are the primary risks associated with PHP 5.6.40: Given the severity of the risks, remaining on PHP 5
The table below breaks down the primary security threats that affect environments running PHP versions less than or equal to 5.6.40: CVE Identifier Affected Component Attack Vector Severity Impact Mbstring Extension Malformed regular expressions Critical System Compromise CVE-2019-6977 GD Graphics Library Crafted image data input Heap Buffer Overflow CVE-2019-9020 XML-RPC Extension Malicious XML-RPC payloads Read-After-Free / RCE CVE-2019-9021 PHAR Archive Module Malformed archive filenames Memory Disclosure Cascading Security Flaws
PHP Version History: Timeline from 1.0 to 8.5 (2026 Update) - Cloudways
PHP 7 and 8 brought significant syntax changes. Code must be updated to be compatible with PHP 8.x.
The PHAR (PHP Archive) component contains a use-after-free vulnerability during directory processing. Attackers utilizing malicious .phar files can corrupt system memory to bypass security controls.