: An out-of-bounds read error in the xmlrpc_decode function. Remote attackers could cause memory corruption or information disclosure via a hostile XML-RPC server.
Many vulnerabilities discovered in the PHP 5.x engine since 2019 remain unpatched in 5.6.40, including potential Remote Code Execution (RCE) and Denial of Service (DoS) vectors. Vulnerability Database Resources
Staying on PHP 5.6 is no longer an option. The industry standard in 2026 is PHP 8.2 or higher, with 8.5 being the latest stable branch. php version 5640 vulnerabilities link
Attackers can exploit flaws in older PHP versions to execute arbitrary code on the server, gaining full control over the website and underlying infrastructure.
Migrate your server environment to PHP 8.x, which offers superior performance and security. : An out-of-bounds read error in the xmlrpc_decode function
After 5.6.40 was released, many critical CVEs were discovered that affect the 5.6 branch but were for 5.6.x. Examples include:
Running PHP 5.6.40 means your application is exposed to numerous publicly known vulnerabilities that will never be patched by the PHP Group. As indicated by Influential Software , running unsupported software is not a viable strategy for any organization concerned with data integrity. Key Security Vulnerabilities Vulnerability Database Resources Staying on PHP 5
For government-grade tracking, use the NVD:
PHP version 5.6.40 was released on January 10, 2019 , as a final security release for the 5.6 branch. While 5.6.40 itself addressed several issues, it has since reached its official End of Life (EOL)
Before making any changes, back up your website files and databases.
Because 5.6.40 is EOL, any vulnerability discovered after Jan 2019 remains unpatched in this version. Notable examples: