PHP 5.6.37 was released in June 2018, but it carries significant security vulnerabilities that put your website at risk. Three critical CVEs have been identified in this version, including two high-severity flaws that could allow attackers to access sensitive files, crash your application, or exploit buffer overflow vulnerabilities. If your website is still running PHP 5.6.37, you're among approximately 318 sites operating with known security weaknesses.
These vulnerabilities aren't theoretical—they're actively exploitable and have been documented in security databases worldwide. The good news is that identifying and fixing them is straightforward. This guide will walk you through understanding these threats, checking if you're affected, and implementing secure solutions to protect your website and users.
PHP 5.6.37 is an older version of PHP, the server-side programming language that powers millions of websites worldwide. Released in 2018, it was designed to process code on your web server and generate the content visitors see in their browsers. Think of PHP as the engine behind your website—it handles everything from processing form submissions to retrieving data from databases and generating dynamic pages.
PHP versions are numbered sequentially, and 5.6.37 belongs to the older 5.6 branch. While it was stable for its time, the internet's security landscape has evolved dramatically since 2018. Hackers have discovered new ways to exploit software, and older PHP versions become increasingly vulnerable as new attack methods emerge. Using outdated PHP versions is like using an old lock on your front door—it might have worked fine years ago, but modern thieves have new tools designed to break through it.
3 CVEs found. The most critical are explained below.
PHP has a flaw when reading thumbnail data from image files. If someone uploads a specially crafted image, it could cause the server to read memory it shouldn't access, potentially exposing sensitive information or crashing your website.
Impact: Your website could crash when processing certain images, or attackers could leak sensitive data stored in server memory.
↗ View on NVDOn Windows servers, PHP's linkinfo function doesn't properly check file access restrictions. An attacker could use this to discover files and folders on your server that should be hidden from them.
Impact: Attackers can map your server's file structure and find sensitive files, making it easier to plan further attacks.
↗ View on NVDPHP crashes when it encounters a malformed JPEG file with incorrect metadata. An attacker could upload such an image to make your website unavailable to legitimate users.
Impact: Your website becomes temporarily unavailable when a malicious image is processed, affecting customer experience and revenue.
↗ View on NVDScan your site in 30 seconds. Used by 500+ web agencies.
PHP 5.6.37 poses real security risks to your website, with vulnerabilities that could lead to data theft, file disclosure, or service disruption. The longer you delay upgrading, the greater your exposure to potential attacks. Modern PHP versions not only patch these security flaws but also offer significant performance improvements and new features that enhance your website's speed and reliability.
Don't let outdated software compromise your website's security. SiteRecipe.com helps you identify vulnerable technologies across your web presence and provides actionable upgrade paths tailored to your specific needs. Start your free security scan today and take the first step toward a safer, faster website. Your users—and your business—will thank you.
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