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 .
# DANGEROUS - For isolation only FROM php:5.6.40-apache RUN apt-get update && apt-get install -y fail2ban # Disable all network egress except to database
Found in the xmlrpc_decode function, this allows unauthenticated remote attackers to cause a heap out-of-bounds read, potentially leading to system compromise.
The XML-RPC extension allows servers to make procedure calls over networks, but it has historically been a weak point in PHP’s architecture. php version 5640 vulnerabilities verified
Several core functions in PHP 5.6.x (including 5.6.40) have been identified with buffer overflow risks, particularly when processing specially crafted files or strings (e.g., image processing via GD or EXIF data). Application crash (DoS) or arbitrary code execution. Verification: Validated by security researchers at 3. Integer Underflows & Out-of-Bounds Reads
Run php -v on your server to verify the exact build.
Inspect incoming POST requests for suspicious serialized data strings ( O: , a: , s: syntax). 4. Disable Dangerous Functions An attacker scanning for vulnerable servers will treat
Several core extensions inside PHP 5.6.40 contain confirmed memory validation errors: PHP 5.6: Why you should upgrade - Influential Software
PHP 5.6.40 is significantly slower and consumes far more memory than modern equivalents. PHP 8.x versions can process up to three times as many requests per second while drastically lowering infrastructure hosting costs. Remediation and Mitigation Strategies
This vulnerability occurs when the PHP fopen function is used with a specially crafted URL, allowing an attacker to execute arbitrary code on the server. This vulnerability is particularly severe, as it can lead to remote code execution (RCE) and complete control over the server. Several core functions in PHP 5
Under frameworks like GDPR, HIPAA, or CCPA, failing to secure user data using up-to-date, industry-standard technology leaves your company liable for massive negligence lawsuits if a breach occurs.
, issued by the PHP development team as a final security patch in January 2019. Because the PHP group stopped providing official community security updates immediately after this release, deploying or maintaining PHP 5.6.40 in production exposes infrastructure to severe security gaps. Despite its status as a final patch, security researchers have verified numerous high-severity vulnerabilities affecting this exact release and prior 5.6 iterations.
When security researchers say a vulnerability is verified , they mean:
(multibyte string) regular expression functions. By persuading a user to parse a specially crafted filename or sending malicious multibyte sequences, a remote attacker could trigger a buffer over-read. This could lead to sensitive information disclosure or, in some cases, a complete system compromise. Arbitrary Code Execution (ACE):