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Home / Blog / PHP 5.4.45
Security Advisory

PHP 5.4.45 Critical Vulnerabilities: 7 CVEs Explained

📅 June 07, 2026 ·⏱ 5 min read ·🔒 SiteRecipe Security Team
3,452 websites still running PHP 5.4.45  → View full list
7
Total
2
Critical
4
High
1
Medium

PHP 5.4.45 is an outdated version that poses serious security risks to your website. Released in 2015, this version contains 7 known vulnerabilities, including 2 critical-level flaws that could allow attackers to execute arbitrary code on your server. If your site still runs PHP 5.4.45, you're potentially exposing sensitive data and putting your business at risk.

With over 3,452 websites still using this vulnerable version, the threat is real and immediate. Attackers actively target outdated PHP installations, knowing that many site owners haven't kept up with security patches. This guide will help you understand these vulnerabilities, identify if you're affected, and take action to protect your website.

What is Php 5.4.45?

PHP 5.4.45 is a version of PHP, the programming language that powers approximately 77% of all websites on the internet. PHP is what runs behind the scenes on your website, handling everything from processing contact forms to managing databases and displaying dynamic content. Think of it as the engine that makes your website function—when that engine has security holes, your entire site is at risk.

PHP versions are numbered sequentially, and each version eventually becomes outdated and no longer receives security updates. PHP 5.4.45 reached the end of its support lifecycle years ago, meaning developers no longer patch new security issues discovered in this version. Using an unsupported PHP version is like driving a car with known mechanical problems—you might get away with it for a while, but eventually something will break catastrophically.

Key Vulnerabilities in Php 5.4.45

7 CVEs found. The most critical are explained below.

CRITICAL CVE-2015-6834 9.8/10 · CVSS v3.0 ⏱ Immediate
Remote Code Execution Through Corrupted Data Objects

Attackers can send specially crafted data to your website that exploits how PHP handles certain data storage objects. This causes PHP to access memory incorrectly, allowing hackers to run their own code on your server.

Impact: Complete server compromise - attackers could steal all your data, modify your website, or use your server to attack others.

↗ View on NVD
CRITICAL CVE-2015-6835 9.8/10 · CVSS v3.0 ⏱ Immediate
Session Data Corruption Leading to Code Execution

Your website uses sessions to remember logged-in users. Attackers can manipulate this session data to trick PHP into running malicious code when the session is processed.

Impact: Attackers could gain unauthorized access, execute code with your website's permissions, or crash your site.

↗ View on NVD
HIGH CVE-2016-3171 8.1/10 · CVSS v3.0 ⏱ Immediate
Drupal and PHP Session Truncation Vulnerability

If you run Drupal on this PHP version, attackers can exploit how session data is handled to execute code on your server.

Impact: Your website could be compromised, allowing attackers to steal data or take control of your site.

↗ View on NVD
HIGH CVE-2015-6837 7.5/10 · CVSS v3.0 ⏱ Within 7 days
XML Processing Memory Crash

If your website processes XML data (common in web services), attackers can send malformed XML to crash PHP or potentially execute code.

Impact: Your website could experience service interruptions or be compromised depending on how PHP is configured.

↗ View on NVD
HIGH CVE-2015-6838 7.5/10 · CVSS v3.0 ⏱ Within 7 days
XML Processing Memory Vulnerability

Similar to CVE-2015-6837, this affects XML processing and can crash PHP or lead to code execution through memory mismanagement.

Impact: Service disruption or potential server compromise through XML data handling.

↗ View on NVD
HIGH CVE-2015-6836 7.3/10 · CVSS v3.0 ⏱ Immediate
SOAP Web Service Code Execution

If your website uses SOAP (a web service protocol), attackers can send specially formatted data that confuses PHP's type system and execute arbitrary code.

Impact: Complete server compromise with ability to steal data or control your website.

↗ View on NVD

Additional Vulnerabilities (1 more)

Showing first 10 of 1. View all on NVD ↗

CVE IDSeverityScore PublishedDescription
CVE-2014-9767 MEDIUM 4.3 2016-05-22 Directory traversal vulnerability in the ZipArchive::extractTo function in ext/zip/php_zip.c in PHP before 5.4.45, 5.5.x before 5.5.29, and 5.6.x before 5.6.13 and ext/zip/ext_zip…
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How to Check If Your Website Is Affected

How to Fix These Vulnerabilities

Conclusion

Upgrading from PHP 5.4.45 is not optional—it's essential for the security and survival of your website. The two critical vulnerabilities in this version allow attackers to execute arbitrary code, potentially stealing your data, injecting malware, or taking your site offline entirely. The longer you wait, the higher your risk becomes.

Don't let your website become another security statistic. Use SiteRecipe.com's vulnerability scanner to automatically detect outdated software, insecure configurations, and other security issues across your site. Our platform makes it easy to identify problems and track your remediation progress. Start your free security audit today and sleep soundly knowing your website is protected from known threats.

Frequently Asked Questions

How critical are these vulnerabilities really?
The two critical vulnerabilities (CVE-2015-6834 and CVE-2015-6835) allow remote attackers to execute arbitrary code on your server without any special access. This means attackers can steal data, install backdoors, send spam, or completely compromise your website. These are among the most dangerous types of security flaws possible.
Will upgrading PHP break my website?
Most modern websites work fine with newer PHP versions, but some older sites may experience compatibility issues. This is why backing up your site and testing thoroughly before upgrading is crucial. Your hosting provider can help with the migration, and many offer easy rollback options if problems occur.
Is there a quick fix without upgrading?
No—the only real solution is upgrading to a supported PHP version like 7.4 or 8.1. Security patches cannot be applied to PHP 5.4.45 since it's no longer maintained. Upgrading is not just recommended; it's essential for website security.
Why is my hosting provider still offering PHP 5.4.45?
Some hosting providers keep old versions available for legacy websites, but they don't actively recommend them. If PHP 5.4.45 is available on your host, ask them about the security risks and request an upgrade to a supported version. Responsible hosts should be pushing users away from dangerous outdated versions.

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DISCLAIMER: This report is based on publicly available CVE data from the National Vulnerability Database (NVD) maintained by NIST. Detection of a technology version does not confirm active exploitation on any specific website. For informational purposes only. SiteRecipe is not responsible for actions taken based on this report. Always consult a qualified security professional.

Source: nvd.nist.gov · Published: June 07, 2026 · SiteRecipe.com