Version 5640 Vulnerabilities Verified | Php

Note: There is no officially released version "PHP 5.6.40" with an appended "0" (i.e., 5.6.400). The likely intent refers to PHP 5.6.40 (the final official security release before End-of-Life) or a typo for PHP 5.6.40. This article will address PHP 5.6.40 as the last milestone of the PHP 5.6 branch, verifying its known vulnerabilities and why any version like "5640" is a critical red flag.

References for Further Verification

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 Version 5.6.40 Vulnerabilities Verified: What You Need to Know

PHP is one of the most widely used programming languages on the web, powering over 80% of websites, including popular platforms like WordPress, Facebook, and Wikipedia. However, its popularity also makes it a prime target for hackers and cyber attackers. Recently, a new version of PHP, version 5.6.40, was released, which has been verified to fix several vulnerabilities. In this article, we will take a closer look at these vulnerabilities, their impact, and what you need to do to protect your website.

What is PHP?

PHP (Hypertext Preprocessor) is a server-side scripting language used for web development. It is a free, open-source language that is widely used for creating dynamic web pages, web applications, and content management systems. PHP is known for its simplicity, flexibility, and ease of use, making it a popular choice among web developers.

What are PHP vulnerabilities?

PHP vulnerabilities refer to weaknesses or flaws in the PHP language or its implementations that can be exploited by attackers to gain unauthorized access to a website or web application. These vulnerabilities can be used to execute malicious code, steal sensitive data, or disrupt website functionality. PHP vulnerabilities can arise from various sources, including bugs in the PHP code, insecure coding practices, or outdated software.

PHP Version 5.6.40 Vulnerabilities Verified

On February 13, 2020, the PHP development team released PHP version 5.6.40, which is a security release that fixes several vulnerabilities. These vulnerabilities were reported by security researchers and developers, and they have been verified by the PHP team. The vulnerabilities fixed in PHP 5.6.40 include:

  1. CVE-2019-20503: A use-after-free vulnerability in the array_merge function that could allow an attacker to execute arbitrary code.
  2. CVE-2019-20504: A buffer over-read vulnerability in the xmlrpc extension that could allow an attacker to disclose sensitive information.
  3. CVE-2019-20505: A use-after-free vulnerability in the mb_check_encoding function that could allow an attacker to execute arbitrary code.

Impact of PHP Vulnerabilities

The impact of PHP vulnerabilities can be severe, depending on the nature of the vulnerability and the attacker's intentions. Some possible consequences of PHP vulnerabilities include:

  1. Code injection: Attackers can inject malicious code into a website or web application, leading to data breaches, website defacement, or malware distribution.
  2. Data theft: Attackers can steal sensitive data, such as user credentials, credit card numbers, or personal data.
  3. Website disruption: Attackers can disrupt website functionality, leading to downtime, errors, or unexpected behavior.
  4. Malware distribution: Attackers can use PHP vulnerabilities to distribute malware, such as viruses, Trojans, or ransomware.

How to Protect Your Website

To protect your website from PHP vulnerabilities, follow these best practices:

  1. Update to PHP 5.6.40: If you are using an earlier version of PHP, update to PHP 5.6.40 as soon as possible.
  2. Use a reputable PHP version: Use a reputable PHP version, such as PHP 7.x or PHP 5.6.x, which are actively maintained and supported.
  3. Keep your PHP installation up-to-date: Regularly update your PHP installation to ensure you have the latest security patches and fixes.
  4. Use a web application firewall (WAF): Consider using a WAF to detect and prevent common web attacks, including those targeting PHP vulnerabilities.
  5. Monitor your website: Regularly monitor your website for suspicious activity, such as unusual traffic patterns or error messages.

Conclusion

PHP version 5.6.40 vulnerabilities have been verified, and it is essential to update to this version to protect your website from potential attacks. By understanding the nature of PHP vulnerabilities and taking proactive measures to secure your website, you can prevent data breaches, website disruption, and other security incidents. Remember to keep your PHP installation up-to-date, use a reputable PHP version, and monitor your website for suspicious activity.

Additional Resources

By following these best practices and staying informed about PHP vulnerabilities, you can ensure the security and integrity of your website and protect your users' sensitive data.

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 php version 5640 vulnerabilities verified

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

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.

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

Security Assessment Report: PHP 5.6.40 Vulnerabilities Status: Verified CriticalRelease Date: January 10, 2019End of Life (EOL): December 31, 2018 Executive Summary

PHP version 5.6.40 was the final "security-only" release for the PHP 5.6 branch. As of April 2026, this version has been unsupported for over seven years. Any vulnerabilities discovered after January 2019 remain unpatched by the official PHP development team, posing a severe risk to data integrity and server security. Key Verified Vulnerabilities

While 5.6.40 addressed several initial flaws, it is susceptible to numerous "Day Zero" exploits and inherited risks, as noted by security researchers at Zend :

Remote Code Execution (RCE): Attackers can execute arbitrary code via heap buffer overflows in core components.

Denial of Service (DoS): Vulnerabilities in the EXIF processing and file upload handling can crash the server.

Information Disclosure: Flaws in how the engine handles memory can lead to the leaking of sensitive system data.

Cryptographic Failures: Outdated SSL/TLS implementations within the PHP 5.6 core do not support modern encryption standards. Risk Analysis Threat Level Description Critical Full System Compromise Unauthorized access to the underlying OS. High Data Breach Potential theft of database credentials and user info. High Compliance Failure

Non-compliance with PCI DSS or GDPR due to unsupported software. Recommendation: Immediate Upgrade Note: There is no officially released version "PHP 5

Running PHP 5.6.40 in a production environment is no longer a viable option according to Influential Software .

Priority 1: Migrate to a supported version (PHP 8.2 or 8.3).

Priority 2: If immediate migration is impossible, use a third-party hardened repository (e.g., TuxCare ) for extended security patches.

Priority 3: Isolate legacy environments behind a robust Web Application Firewall (WAF).

⚠️ Warning: Automated exploit kits specifically target PHP 5.6 due to its widespread legacy use and lack of official patches.

If you tell me more about your specific environment, I can help you with: Compatibility checks for migrating code from 5.6 to 8.x Automated scanning tools to find hidden 5.6 instances Configuration steps for temporary hardening

PHP version 5.6.40 was released on January 10, 2019, as the final scheduled security update for the PHP 5.6 branch. While it fixed several critical issues, it is now officially End-of-Life (EOL) and remains vulnerable to a variety of exploits identified since its release. Key Vulnerabilities in Versions Prior to 5.6.40

Version 5.6.40 was primarily a security release to patch the following verified vulnerabilities:

CVE-2019-9023 (Mbstring): Multiple heap-based buffer over-reads in multibyte regular expression functions that could lead to full system compromise.

CVE-2019-9021 (Phar): A heap-based buffer over-read in PHAR extension reading functions.

CVE-2019-9020 (Xmlrpc): A "Use After Free" vulnerability where invalid input to xmlrpc_decode() could cause memory corruption or information disclosure.

CVE-2016-10166 (GD): An integer underflow in the _gdContributionsAlloc function that could have "unspecified impact". The "Verified" Risk Today

Although 5.6.40 patched these specific bugs, running it today is highly discouraged by the PHP Development Team because: PHP 5.6.40 Release Announcement

PHP Version 5.6.40: Verified Vulnerabilities and the Risks of Outdated Code

Running legacy software is a calculated risk that many organizations take for compatibility reasons. However, for those still using PHP version 5.6.40, that risk has shifted from "calculated" to "critical." While version 5.6.40 was the final security release for the 5.x branch, it reached its official End of Life (EOL) on December 31, 2018.

Today, this version is no longer receiving security patches, meaning any newly discovered flaws remain unpatched. Below is a detailed breakdown of verified vulnerabilities affecting PHP 5.6.40 and why upgrading is no longer optional. 1. High-Severity Verified Vulnerabilities

Despite being the "final" patched version of the 5.6 series, 5.6.40 remains vulnerable to several critical flaws discovered both before and after its release. Heap-Based Buffer Overflows (Multiple CVEs):

CVE-2016-10166: An integer underflow in the _gdContributionsAlloc function allows remote attackers to cause unspecified impact via specially crafted image data. References for Further Verification

CVE-2019-6977: A vulnerability in gdImageColorMatch allows for a heap-based buffer overflow due to improper calculation of allocated buffer sizes. Remote Code Execution (RCE) Risks:

While many RCEs were patched in 5.6.40, the version is frequently targeted by exploits like CVE-2019-11043 (specifically when paired with NGINX and php-fpm), which allows unauthenticated remote attackers to execute arbitrary code on the server. Information Disclosure (PHAR Extension):

CVE-2019-9021: A heap-based buffer over-read in PHAR reading functions allows an attacker to read past actual data in memory by parsing a specially crafted filename. 2. The Legacy Trap: Why 5.6.40 is "Dangerously Stable"

Version 5.6.40 was designed to be the most stable version of PHP 5, but its age now makes it a prime target for automated scanning tools. PHP 5.6.40 Release Announcement

While the specific text "php version 5640 vulnerabilities verified" appears to be a user-generated comment or scan result rather than a single authoritative review, it likely refers to security assessments of PHP version 5.6.40.

PHP 5.6.40 reached its end-of-life (EOL) on December 31, 2018, and no longer receives official security updates from the PHP Group. Vulnerability scanners like Tenable Nessus or Rapid7 often trigger "verified" alerts for this version due to its lack of support and several known issues. Key Verified Vulnerabilities in PHP 5.6.40

Although 5.6.40 was the final release of the 5.6 branch intended to fix previous bugs, it remains susceptible to several critical issues discovered shortly after or persisting in its final state:

Heap-based Buffer Over-reads (CVE-2019-9021, CVE-2019-9023): Issues in the PHAR and mbstring extensions allow remote attackers to disclose sensitive information or potentially compromise the system.

Out-of-Bounds Reads (CVE-2019-9020, CVE-2019-9024): Vulnerabilities in the xmlrpc_decode function can lead to system instability or information disclosure when processing malicious requests.

Remote Code Execution (RCE) via PHP-FPM (CVE-2019-11043): While often associated with newer versions, certain configurations of PHP-FPM on Nginx servers remain a high-risk factor for older stacks.

Third-Party Dependencies: Versions of Docker images running PHP 5.6.40 often contain critical vulnerabilities in bundled libraries like libcurl (e.g., stack-based buffer overflows). Recommendations

Security experts and repositories like the NVD - Detail and TuxCare recommend the following: Security backports for EOL PHP version 5.6.40 · GitHub

Part 6: Remediation – You Must Migrate or Isolate

There is no patch. No backport. No savior. Here is your action plan.

Part 2: Verified Critical Vulnerabilities in PHP 5.6.40

Below are the most severe, verified CVEs (Common Vulnerabilities and Exposures) affecting PHP 5.6.40. These are not theoretical; they have active exploit paths.

Long-term (Within 1 month – Mandatory)

  • Migrate to PHP 8.2 or 8.3. Use tools like Rector to automate code upgrades.
  • If migration is impossible: Air-gap the server. No internet access, no public IP. Internal VPN access only.

D. Third-Party Library Incompatibility

While this is an indirect vulnerability, it is a verified risk. Modern Composer packages now require PHP 7.4 or 8.x. Using PHP 5.6.40 forces developers to use outdated versions of libraries (like Guzzle, Laravel, or Symfony components).

  • The Trap: The PHP core might be stable, but the dependencies it runs have known, verified vulnerabilities that cannot be patched without upgrading PHP.

3. CVE-2018-19935 (Backported but Insufficient)

  • Nature: Use-After-Free
  • Details: The ext/imap extension allows remote attackers to cause a use-after-free via a crafted email message. While fixed in 5.6.39, the fix was incomplete. By 5.6.40, several bypasses existed.

1. PHP 5.6.40: Context & End-of-Life

  • Release Date: January 10, 2019
  • End of Life (Security Support): December 31, 2018 (per official PHP.net)
  • Note: 5.6.40 was a post-EOL security release — only critical issues were patched.
  • Current Status: Unsupported — no security fixes since early 2019.

Even at the time of 5.6.40’s release, several known vulnerabilities remained unpatched or were backported incompletely.

Executive Summary

PHP 5.6.40 has reached End of Life (EOL) . Extensive verification confirms that this version contains multiple unpatched, high-risk vulnerabilities. Continued use in a production environment is classified as a critical security risk.

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