Php Version 5640 Vulnerabilities Link (2026)

Important Note: There is no official PHP version "5.6.40" in the standard PHP release history. The official versions were 5.6.39 and then 5.6.40 (Release Date: Jan 10, 2019). However, given the high likelihood of a typo, this post covers PHP 5.6.40 (the last official security release of the 5.6 branch) and also addresses the possibility you meant the 5.6.4.0 alpha build or a general search for CVE links.

6. Summary

| Question | Answer | |----------|--------| | Is PHP 5.6.40 safe? | No. Over 200 unpatched vulnerabilities. | | Official CVE link for 5.6.40? | Use CVE Details PHP 5.6 + filter by date > Jan 2019. | | Should I migrate? | Yes, urgently. PHP 5.6 is dead software. |

Last updated: 2026-04-19
Disclaimer: Always verify vulnerabilities against your exact PHP version string using php -v and cross-reference with the NVD database.

PHP version 5.6.40, released in January 2019, was the final security update for the PHP 5.6 branch and is now end-of-life (EOL). While it addressed several critical issues, it remains vulnerable to newer exploits discovered after its support ended. Core Vulnerabilities Addressed in PHP 5.6.40

The 5.6.40 release specifically fixed the following critical security flaws:

Buffer Overflows & Underflows: Fixed multiple heap-based buffer overflows in the mbstring extension (CVE-2019-9023) and an integer underflow in the gd graphics library (CVE-2016-10166).

Out-of-Bounds Reads: Resolved issues in the xmlrpc_decode function (CVE-2019-9020) and the PHAR extension (CVE-2019-9021) that could lead to memory disclosure.

Remote Code Execution (RCE): Addressed flaws that unauthenticated, remote attackers could exploit to compromise systems entirely. Post-Release Risks (EOL Status)

Because PHP 5.6.40 is no longer maintained, it is susceptible to vulnerabilities found in later versions of PHP that were never backported. A major example is CVE-2024-4577, a critical remote code execution flaw in PHP-CGI on Windows that impacts all legacy versions. Security Documentation & Papers

Official ChangeLog: The PHP 5 ChangeLog provides the definitive list of bugs fixed in the 5.6.40 release.

Vulnerability Databases: Detailed technical breakdowns of each CVE associated with this version can be found on CVE Details and Tenable.

Academic/Research Context: For a broader look at PHP security, papers like the USENIX study on SSRF-Defenses in PHP Applications discuss modern attack vectors that still affect legacy environments. PHP 5.6.x < 5.6.40 Multiple vulnerabilities. | Tenable®

PHP version 5.6.40 was released on January 10, 2019, as the final security release for the PHP 5.6 branch. While it addressed several critical security bugs at the time, it reached its official End of Life (EOL) on December 31, 2018, meaning it has not received official security updates or bug fixes for over seven years. Key Vulnerabilities in PHP 5.6.40

Although 5.6.40 was a "security release," it remains vulnerable to numerous exploits discovered after its EOL. Because the PHP project no longer maintains this branch, any vulnerability found since 2019 remains unpatched in official builds.

Heap-Based Buffer Over-reads (CVE-2019-9023): This critical vulnerability occurs in mbstring regular expression functions when they are supplied with invalid multibyte data. It can allow a remote attacker to compromise the target system.

PHAR Reading Issues (CVE-2019-9021): A heap-based buffer over-read in the PHAR extension may allow attackers to read memory past actual data while parsing filenames.

Integer Underflow (CVE-2016-10166): An issue in the _gdContributionsAlloc function in gd_interpolation.c can have unspecified impacts via unauthenticated remote attacks.

Exposed phpinfo() Page: While not a vulnerability in the code itself, many legacy 5.6.40 setups leave the phpinfo() page public, which discloses sensitive server information that aids in formulating Remote Code Execution (RCE) or Local File Inclusion (LFI) attacks. Security Risk Summary

Using PHP 5.6.40 in 2026 is considered high-risk. Automated scanners frequently identify hundreds of known vulnerabilities in environments running this version. Snyk - Vulnerability report for Docker php:5.6.40-apache

The PHP version 5.6.40 has several known vulnerabilities. Here are some resources and guidelines to help you understand and mitigate these issues:

1. Official Vulnerability Sources & Links

Recommendation

PHP 5.6.40 should NOT be used in production - it has many known, unpatched vulnerabilities. Upgrade to PHP 7.4+ (or PHP 8.x) immediately for security.

You're referring to PHP version 5.6.40, which has several known vulnerabilities. To address these concerns, I'll outline a feature that can help mitigate these issues.

Feature: "PHP Vulnerability Shield"

Description: A PHP module that provides an additional layer of security to prevent exploitation of known vulnerabilities in PHP 5.6.40. This module will:

1. Monitor and filter incoming requests: Analyze incoming requests for suspicious patterns and block requests that may be attempting to exploit known vulnerabilities.
2. Disable vulnerable functions: Identify and disable functions that are known to be vulnerable, preventing their use even if an attacker tries to exploit them.
3. Provide updates and patches: Offer a mechanism to easily apply security patches and updates to vulnerable functions, ensuring the system stays protected.

Key Components:

1. Vulnerability Database: A comprehensive database of known vulnerabilities in PHP 5.6.40, which will be used to identify and block suspicious requests.
2. Request Analyzer: A component that analyzes incoming requests and checks them against the vulnerability database.
3. Function Disabler: A feature that disables vulnerable functions to prevent exploitation.
4. Patch Manager: A tool that allows for easy application of security patches and updates.

Implementation:

1. Create a vulnerability database with a list of known vulnerabilities in PHP 5.6.40.
2. Develop a request analyzer that checks incoming requests against the vulnerability database.
3. Implement a function disabler that disables vulnerable functions.
4. Design a patch manager that allows for easy application of security patches and updates.

Example Code:

// Vulnerability Database
$vulnerabilityDB = [
    'function_name' => [
        'vulnerability_description',
        'exploit_pattern',
    ],
    // ...
];
// Request Analyzer
function analyzeRequest($request) 
    global $vulnerabilityDB;
    foreach ($vulnerabilityDB as $function => $vulnerability) 
        if (preg_match($vulnerability['exploit_pattern'], $request)) 
            // Block the request
            return false;
return true;
// Function Disabler
function disableVulnerableFunctions() 
    global $vulnerabilityDB;
    foreach ($vulnerabilityDB as $function => $vulnerability) 
        // Disable the function
        function_exists($function) && eval("unset($$function);");
// Patch Manager
function applyPatch($patch) 
    // Apply the patch
    // ...

Benefits:

1. Improved Security: The PHP Vulnerability Shield provides an additional layer of security, protecting against known vulnerabilities in PHP 5.6.40.
2. Easy Maintenance: The patch manager allows for easy application of security patches and updates, reducing the burden on system administrators.
3. Flexibility: The module can be easily updated to address new vulnerabilities and PHP versions.

This feature can be integrated into existing PHP applications, providing a robust security solution for PHP 5.6.40.

PHP version 5.6.40 was released on January 10, 2019 , as a final security release for the 5.6 branch. While 5.6.40 itself addressed several issues, it has since reached its official End of Life (EOL)

and no longer receives security patches from the PHP development team.

Detailed lists of historical vulnerabilities and CVEs for this version can be found on CVE Details Blog Post: The Hidden Risk of PHP 5.6.40 in 2026 If you are still running PHP 5.6.40

, you are essentially driving a car with a 2019 inspection sticker—it might still run, but it’s no longer safe for the road.

As of April 2026, PHP 5.6.40 has been officially unsupported for over seven years. While it was intended to be the most secure version of the 5.6 series at the time of its release, the threat landscape has evolved drastically since then. Why "Final Security Release" is a Misnomer

When PHP 5.6.40 dropped in early 2019, it was the "last scheduled release". However, "final" doesn't mean "invulnerable." It simply means the PHP team stopped looking for bugs in that branch. Any vulnerability discovered since then—of which there have been many—remains in your environment. Critical Vulnerabilities at a Glance

Systems running PHP 5.6.40 or earlier are susceptible to several high-impact exploits: PHP PHP 5.6.40 security vulnerabilities, CVEs

This page lists vulnerability statistics for CVEs published in the last ten years, if any, for PHP » PHP » 5.6. 40 . CVE Details Unsupported Branches - PHP

PHP version 5.6.40 was released on January 10, 2019, as a final security release for the PHP 5.6 branch. Because PHP 5.6 reached official End of Life (EOL) shortly after this release, it no longer receives official security updates, leaving it vulnerable to any flaws discovered after that date. Core Vulnerabilities Addressed by Upgrading to 5.6.40

Users running versions prior to 5.6.40 are affected by several critical vulnerabilities that this specific release was designed to patch:

Heap-based Buffer Over-read (CVE-2019-9020 / CVE-2019-9024): Flaws in the xmlrpc_decode function could allow a remote attacker to cause a system compromise or read memory outside of allocated areas via specially crafted requests.

PHAR Extension Memory Disclosure (CVE-2019-9021): Improper memory operations in PHAR reading functions could allow an attacker to disclose sensitive information by persuading a user to parse a crafted filename.

Buffer Overflows in mbstring (CVE-2019-9023): Regular expression functions in the mbstring component were found to have vulnerabilities that could lead to a complete system compromise through crafted multibyte sequences.

Integer Underflow (CVE-2016-10166): An issue in the _gdContributionsAlloc function could lead to unspecified remote impact. Risks of Remaining on 5.6.40

Since 5.6.40 is the last scheduled release, it remains vulnerable to newer threats discovered after 2019, such as:

Surviving PHP 7 End of Life: Best Practices for a Secure Transition

PHP 5.6.40, which reached end-of-life on December 31, 2018, is vulnerable to numerous security risks, including heap-based buffer overflows (CVE-2019-9023, CVE-2019-6977) and arbitrary code execution, due to a lack of security patches. Continued use of this version poses significant compliance risks, such as violating PCI DSS and GDPR standards, while hindering performance compared to PHP 8.x. For more information on the release, see the PHP 5.6.40 Release Announcement endoflife.date PHP | endoflife.date

PHP 5.6.40 in a production environment is a major security risk because it reached its End of Life (EOL) on December 31, 2018

. Since that date, the official PHP development team has provided no security updates or bug fixes

for this version, leaving it permanently exposed to any vulnerabilities discovered over the last several years. Critical Vulnerabilities in PHP 5.6.40

While PHP 5.6.40 was the final security release for the 5.6 branch, it is still susceptible to numerous unpatched flaws and inherited issues. Key risks include: Remote Code Execution (RCE): Flaws in core extensions like ext/session

can allow attackers to execute arbitrary code on your server through type confusion or use-after-free issues. Heap-based Buffer Over-reads: Vulnerabilities in the reading functions and extension (e.g., CVE-2019-9021 CVE-2019-9023 php version 5640 vulnerabilities link

) can be exploited to read sensitive memory or cause a complete system compromise. Integer Underflows and Overflows:

Improper implementation of memory operations in functions like gdImageColorMatch CVE-2019-6977

) can lead to unauthorized data access or application crashes. Out-of-Bounds Reads: xmlrpc_decode CVE-2019-9024

) can allow a hostile server to read data outside of allocated memory. Why You Must Upgrade

Staying on 5.6.40 is often referred to as "leaving your front door unlocked".

PHP 5.6.40 is the final security release of the PHP 5.6 branch and reached its official End of Life (EOL) on December 31, 2018. Because official support has ended, no new security patches are released by the PHP Group, leaving any newly discovered flaws unpatched.  Critical Vulnerabilities Summary 

While 5.6.40 addressed several bugs from earlier 5.6.x versions, it remains susceptible to various vulnerabilities depending on the specific environment and extensions used: 

Integer Underflow (CVE-2016-10166): Affects the gd_interpolation.c file in the GD extension. Remote attackers can cause unspecified impacts by manipulating certain variables.

Heap-Based Buffer Overflow (CVE-2019-6977): Exists in the gdImageColorMatch function. This can be exploited by calling the function with crafted image data, potentially leading to arbitrary code execution.

XMLRPC Decode Heap Buffer Over-read: A flaw in the xmlrpc_decode function that can lead to information disclosure or crashes.

Legacy Flaws: Many vulnerabilities discovered in the PHP 5.x engine since 2019 remain unpatched in 5.6.40, including potential Remote Code Execution (RCE) and Denial of Service (DoS) vectors.  Vulnerability Database Resources 

For a complete, real-time list of all Common Vulnerabilities and Exposures (CVEs) associated with this version, refer to these primary tracking links: 

CVE Details - PHP 5.6.40: Provides a comprehensive table of all known vulnerabilities, including CVSS scores and impact types.

NVD Search (NIST): The official U.S. government repository of standards-based vulnerability management data.

Tenable Nessus Plugins for PHP 5.6.40: Details on how security scanners identify and report risks for this specific version.  Risk Assessment & Recommendation  Risk Factor  Assessment Patch Status Critical (No further updates from PHP.net) Compliance Non-compliant (Fails most PCI-DSS and HIPAA requirements) Security Risk High (Publicly available exploits for multiple CVEs) Immediate Action Required: 

Upgrade: Move to a supported version (e.g., PHP 8.2 or 8.3) to receive security updates.

Mitigation: If an upgrade is not immediately possible, use a Web Application Firewall (WAF) and strictly sanitize all user inputs. 

PHP Vulnerabilities: Assessment, Prevention, and Mitigation - Zend

PHP version 5.6.40 was released on January 10, 2019 , as a final security update to address several critical bugs. Official security support for the entire PHP 5.6 branch ended on December 31, 2018

, meaning version 5.6.40 and all prior 5.6.x versions no longer receive official patches for newly discovered flaws. Critical Vulnerabilities in PHP 5.6.40

Because PHP 5.6.40 is end-of-life (EOL), it remains vulnerable to multiple critical issues disclosed since its final release, including: CVE-2024-4577 (Critical - CVSS 9.8):

A remote code execution (RCE) vulnerability that affects PHP running on Windows in CGI configurations. Attackers can bypass previous protections to execute arbitrary commands. Buffer Overflows & Underflows: CVE-2016-10166: An integer underflow in the gd_interpolation.c CVE-2019-6977: A heap-based buffer overflow in gdImageColorMatch Memory Corruption: CVE-2019-9020: A heap-based buffer over-read in xmlrpc_decode that can lead to system compromise. CVE-2019-9021:

A heap-based buffer over-read in the PHAR extension allowing attackers to read memory past actual data. Out-of-Bounds Reads: CVE-2019-9024: An out-of-bounds read error in xmlrpc_decode triggered by a hostile XMLRPC server. Regular Expression Vulnerabilities: CVE-2019-9023: Multiple heap-based buffer over-read instances in regular expression functions. Security Risks of Continued Use

As of 2026, running PHP 5.6.40 poses extreme risks to production environments: PHP Requirements - Knowledgebase - The Events Calendar

The Risks of Using Outdated PHP: Understanding Version 5.6.40 Vulnerabilities and the Importance of Upgrading Important Note: There is no official PHP version "5

PHP is one of the most widely used programming languages on the web, powering millions of websites and web applications. However, like any software, PHP is not immune to security vulnerabilities. In this article, we'll focus on PHP version 5.6.40, a version that has been identified as having several vulnerabilities. We'll explore the risks associated with using outdated PHP versions, the specific vulnerabilities found in version 5.6.40, and why upgrading to a newer version is crucial for maintaining the security and integrity of your website.

The Evolution of PHP and the Importance of Updates

PHP has undergone significant changes and improvements over the years. From its early days as a simple scripting language to its current status as a robust and feature-rich language, PHP has evolved to meet the growing demands of web development. One of the key aspects of PHP's development is its commitment to security. The PHP development team continuously works to identify and patch vulnerabilities, ensuring that newer versions of the language are more secure than their predecessors.

However, this commitment to security means that older versions of PHP, like version 5.6.40, eventually become outdated and vulnerable to known security threats. When a PHP version reaches the end of its life (EOL), it no longer receives security updates or patches, leaving websites that use it exposed to potential security risks.

PHP Version 5.6.40 Vulnerabilities

PHP version 5.6.40, released in 2018, is one such version that has reached its EOL. This version, like many others before it, had its share of vulnerabilities. Some of the notable vulnerabilities found in PHP 5.6.40 include:

1. CVE-2018-14851: A vulnerability in the exif extension that could allow remote attackers to cause a denial of service (DoS) or potentially execute arbitrary code.
2. CVE-2018-14852: A vulnerability in the exif extension that could allow remote attackers to cause a DoS or potentially execute arbitrary code.
3. CVE-2018-7208: A vulnerability in the gif2h function that could allow remote attackers to cause a DoS.

These vulnerabilities, and others like them, were patched in later versions of PHP. However, since PHP 5.6.40 is no longer supported, websites using this version are left to fend for themselves, exposed to these known security risks.

The Risks of Using Outdated PHP Versions

Using an outdated PHP version like 5.6.40 poses significant risks to your website and its users. Some of the potential consequences include:

1. Security breaches: Known vulnerabilities in outdated PHP versions can be exploited by attackers to gain unauthorized access to your website, leading to potential data breaches or other malicious activities.
2. Malware infections: Outdated PHP versions can be used to spread malware, which can infect your website and harm your users.
3. Denial of Service (DoS) attacks: Vulnerabilities in outdated PHP versions can be used to launch DoS attacks, which can render your website unavailable to users.
4. Loss of user trust: If your website is compromised due to an outdated PHP version, you risk losing the trust of your users, which can have long-term consequences for your business or organization.

The Benefits of Upgrading to a Newer PHP Version

Upgrading to a newer PHP version is essential for maintaining the security and integrity of your website. Some of the benefits of upgrading include:

1. Improved security: Newer PHP versions include patches for known vulnerabilities, reducing the risk of security breaches and other malicious activities.
2. New features and improvements: Newer PHP versions often include new features and improvements that can enhance the performance and functionality of your website.
3. Better support: Newer PHP versions are actively maintained and supported by the PHP development team, ensuring that you have access to help and resources when you need them.
4. Compliance with best practices: Upgrading to a newer PHP version demonstrates your commitment to best practices in web development, which can enhance your reputation and build trust with your users.

Conclusion

Using an outdated PHP version like 5.6.40 poses significant risks to your website and its users. The known vulnerabilities in this version, and others like it, can be exploited by attackers to gain unauthorized access to your website, leading to potential security breaches, malware infections, and other malicious activities. Upgrading to a newer PHP version is essential for maintaining the security and integrity of your website, and it also provides access to new features, improvements, and better support. Don't wait until your website is compromised – upgrade to a newer PHP version today and ensure the security and trust of your users.

Resources

• PHP official website: https://www.php.net/
• PHP version 5.6.40 changelog: https://github.com/php/php-src/blob/php-5.6.40/NEWS
• PHP security documentation: https://www.php.net/manual/en/security.php

By taking the necessary steps to upgrade to a newer PHP version, you can ensure the security and integrity of your website, protect your users, and maintain compliance with best practices in web development.

PHP version 5.6.40 was the final security release for the PHP 5.6 branch. While its release in early 2019 fixed several critical issues, it is now officially End of Life (EOL) and has not received official security patches since late 2018. Critical Vulnerabilities Fixed in 5.6.40

Version 5.6.40 was primarily released to address the following critical and high-severity flaws found in earlier 5.6.x versions:

CVE-2019-9021 (Severity: 9.8 Critical): A heap-based buffer over-read in mbstring regular expression functions. A remote attacker could send crafted multibyte sequences to cause a system compromise or crash.

CVE-2019-9023 (Severity: 9.8 Critical): An out-of-bounds read error in the xmlrpc_decode function. Remote attackers could cause memory corruption or information disclosure via a hostile XML-RPC server.

CVE-2019-9020 (Severity: 7.5 High): A heap-based buffer over-read in PHAR reading functions. Attackers could exploit this via crafted file names to disclose sensitive information.

CVE-2019-9024 (Severity: 7.5 High): Another out-of-bounds read in xmlrpc_decode related to base64 decoding. Post-5.6.40 Risks

Because 5.6.40 is the final version of an unsupported branch, any vulnerabilities discovered after its release remain unpatched in official builds. Significant threats include: PHP 5.6: Why you should upgrade - Influential Software

Official Sources

1. PHP.net ChangeLog (most authoritative)

   • Direct link: https://www.php.net/ChangeLog-5.php#5.6.40
   • This shows all security fixes and bugs fixed in version 5.6.40

2. CVE Details for PHP 5.6

   • https://www.cvedetails.com/product/128/PHP-PHP.html?vendor_id=74
   • Filter by version 5.6.x

What Does "End-of-Life" Mean for Security?

When software reaches EOL, the developers stop releasing updates—period. This means: CVE Details for PHP 5.6

1. No Bug Fixes: If a function breaks in a new OS environment, it stays broken.
2. No Security Patches: If a hacker discovers a zero-day vulnerability today, there will never be a patch released for PHP 5.6.40.
3. Compliance Issues: Running EOL software almost universally violates security standards like PCI-DSS, HIPAA, and GDPR.