Current PHP Versions | The Evolution & History of PHP - Zend
What (like WordPress, Drupal, or custom code) is running on this version?
Multiple vulnerabilities in xmlrpc_decode exist, increasing the likelihood of application crashes or data leakage.
The 5.6.40 environment is susceptible to memory corruption issues where a remote attacker can read sensitive memory contents or cause a system hang by providing out-of-range integer values to certain built-in functions. Data leakage and Denial of Service (DoS). Exploitation Scenarios Vulnerability Type Common Vector SQL Injection Unsanitized AJAX parameters or form inputs. Unauthorized database access. Command Injection Use of risky functions like OS-level command execution. Improper output escaping of user data. Session hijacking or credential theft. Recommended Actions Immediate Upgrade: Migrate to a supported version, such as PHP 8.2, 8.3, or 8.4 Disable Risky Functions: If an immediate upgrade is impossible, add shell_exec disable_functions directive in your Input Validation: validate and sanitize
Restrict dangerous functions in your php.ini file to minimize the impact of a potential remote code execution vulnerability: php version 5640 vulnerabilities verified
An attacker scanning for vulnerable servers will treat any version string containing 5.6.40 or its numerical equivalent (5640 in a format string) as a high-value, low-effort target .
PHP 5 did not have the modern sodium or argon2 libraries integrated. Using MD5 or SHA1 for passwords is negligent. While PHP 5.5+ introduced password_hash() using Bcrypt, it is the bare minimum.
To protect your PHP applications from the verified vulnerabilities in PHP version 5.6.40, follow these best practices:
1. Remote Code Execution via Exif Extension (CVE-2019-11034, CVE-2019-11035) Current PHP Versions | The Evolution & History
When security researchers say a vulnerability is verified , they mean:
This permitted full Remote Code Execution (RCE), allowing threat actors to completely compromise the underlying server infrastructure. 2. Core Engine and Extension Memory Corruption Flaws
As an unsupported "End-of-Life" version, PHP 5.6.40 no longer receives security updates, meaning any vulnerabilities discovered after early 2019 remain unpatched. Verified Vulnerabilities in PHP 5.6.40
Requires maintaining a secure network and using updated, supported software. Running PHP 5.6.40 will trigger an automatic fail on an ASV (Approved Scanning Vendor) compliance scan. Data leakage and Denial of Service (DoS)
Then deploy with – only via a secure jump host.
PHP 5.6.40 is a security liability. With verified vulnerabilities allowing for full system compromises, continuing to use it in 2026 is extremely risky. The security, performance, and compliance benefits of upgrading to PHP 8.x make the transition necessary for any serious web project. I can help you:
Never use == for security checks. Always use === (strict comparison).