5640 Vulnerabilities Verified | Php Version

Need help validating your specific PHP build? Contact a web security firm for a penetration test—but expect them to immediately flag PHP 5.6.40 as a critical finding.

PHP 5.6.40, released in January 2019, is the final security release of the PHP 5.6 branch

. While it was designed to fix critical flaws present in earlier 5.6.x versions, it is now End-of-Life (EOL)

and remains vulnerable to high-severity exploits discovered after its support period Critical Vulnerabilities Affecting PHP 5.6.40

Although 5.6.40 was a "security fix" release, newer research has identified critical flaws that still impact this version because it no longer receives official patches: CVE-2024-4577 (CGI Argument Injection) Critical (CVSS 9.8)

vulnerability that allows remote unauthenticated attackers to execute arbitrary code on Windows servers using Apache and PHP-CGI

. Because PHP 5.6.40 is EOL, it has not received an official patch for this Buffer Overflows & Memory Corruption php version 5640 vulnerabilities verified

: Since official support ended in December 2018, subsequent vulnerabilities in core components (like

) discovered in later years often remain unpatched in 5.6.40 unless a third-party vendor provides backported fixes Cybersecurity Help Legacy Dependency Vulnerabilities

: Many versions of 5.6.40 are bundled with outdated libraries (like ) that have their own critical security flaws (e.g., CVE-2021-22947 Vulnerabilities Fixed If you are upgrading

5.6.40 from an older 5.6 release, it does address these verified issues CVE-2016-10166 : A use-after-free vulnerability in imagescale (GD extension). CVE-2019-9023 : Multiple heap buffer overflows in regular expression functions. CVE-2019-9021 : Heap buffer overflow in phar_detect_phar_fname_ext (PHAR extension). CVE-2019-9020 : Heap out-of-bounds read in xmlrpc_decode() Security Guide & Mitigation

PHP version 5.6.40 was the final release of the PHP 5.6 branch, which reached its end-of-life (EOL) on December 31, 2018. Despite being a maintenance release intended to address final security concerns, it remains vulnerable to several critical flaws discovered post-release. Verified Vulnerabilities in PHP 5.6.40

As an unsupported version, PHP 5.6.40 does not receive official patches for new threats. Verified vulnerabilities associated with this specific version include: Need help validating your specific PHP build

Heap-Based Buffer Over-read (CVE-2019-9020): A flaw in the xmlrpc_decode function exists due to improper validation of input data. Remote attackers can exploit this via specially crafted requests to cause a "read-after-free" condition, potentially leading to a complete system compromise.

Buffer Overflow in GD Library (CVE-2019-6977): A heap-based buffer overflow exists in the gdImageColorMatch function. Attackers can trigger this by calling the function with crafted image data, which can lead to application crashes or arbitrary code execution.

PHAR Extension Information Disclosure: Improper implementation of memory operations in PHAR reading functions allows unauthenticated attackers to disclose sensitive information if they can persuade a user to parse a specially crafted filename.

Integer Underflow (CVE-2016-10166): An integer underflow in the _gdContributionsAlloc function in gd_interpolation.c can be triggered by remote attackers to cause unspecified impacts through the decrementing of variables. Critical Risk Factors

Lack of Security Patches: Since it reached EOL in 2018, it no longer receives updates, leaving all newly discovered vulnerabilities unpatched and open to exploitation.

Target for Automated Attacks: Because many legacy systems still run PHP 5.6, it is a high-priority target for automated exploit kits and unauthenticated SQL injection attacks. After running automated scanners (e

Third-Party Plugin Risks: Many WordPress plugins and extensions developed during the PHP 5.x era (like Article Analytics) have critical, unpatched vulnerabilities (e.g., CVE-2023-5640) that specifically affect legacy environments. Recommendation

Security experts, including those at Zend and Influential Software, strongly advise upgrading to a supported version (such as PHP 8.2 or higher) to protect data and maintain system integrity.

PHP Vulnerabilities: Assessment, Prevention, and Mitigation - Zend

After running automated scanners (e.g., Nessus, WPScan) and manual checks, the following vulnerabilities have been confirmed as present and exploitable in a default installation of PHP 5.6.40:

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.

Older PHP versions often rely on server configuration (like open_basedir) to mitigate path traversal. Core engine improvements in newer versions provide stronger isolation.