While version 5.6.40 addressed several flaws present in earlier 5.6 releases, it remains susceptible to critical vulnerabilities discovered after its EOL date. Major risks identified by security researchers from Tenable and Rapid7 include:
PHP 5.6.40 in 2026 is a critical security risk. Although version 5.6.40 was the final "security fix" release for the PHP 5.6 branch, it reached official End-of-Life (EOL) php version 5640 vulnerabilities verified
The vulnerabilities listed above have been positively verified in our tests. Running this version exposes your application to immediate remote compromise. Upgrade is non-negotiable. While version 5