70% of websites run on PHP, which recently had critical flaws uncovered by AI

PHP is the programming language that runs an estimated 70% of the internet. Recently, critical security vulnerabilities were uncovered in PHP by researchers using AI models from OpenAI. The PHP Foundation has released patched versions of PHP to fix these vulnerabilities, but older versions will not receive official fixes. The coordinated release was brought forward due to public outcry after premature disclosures.

The PHP Foundation has released patched versions PHP 8.2.35, 8.3.36, 8.4.27, and 8.5.12 to fix the vulnerabilities. PHP 8.1 and older versions will not receive official fixes. The coordinated release was originally scheduled for Oct. 22, but was brought forward to Oct. 21 following premature disclosures on Oct. 20, which led to public outcry. OpenAI says every site using PHP can now safely upgrade its version to stay secure.

The two vulnerabilities, tracked as CVE-2026-109618 and CVE-2026-109619, involve flaws in how PHP manages computer memory and handles errors. The first occurs when PHP runs out of allocated memory while processing a request, potentially leaving behind incomplete internal data that the engine may later mistakenly treat as valid. The second involves a related problem in which a fatal error leaves PHP pointing to memory that has already been freed, allowing subsequent requests to access or corrupt it. Under certain conditions, attackers can exploit these weaknesses remotely, without needing login credentials, to execute malicious code on affected servers, potentially taking control of websites.

Using AI, the researchers also demonstrated that the flaws could expose sensitive information stored in server memory, including passwords, authentication tokens, and API keys. Most concerning, the vulnerabilities exist in PHP's core engine, meaning websites can be affected even if their application code has no security flaws. Both vulnerabilities received a critical severity score of 9.2 out of 10.

OpenAI says human developers and security teams examined the underlying code but couldn't fully resolve the flaws, allowing them to persist for two years after discovery. Meanwhile, AI-wielding researchers demonstrated practical ways to exploit it within two weeks. Conversely, one could argue that the flaws would never have been exploitable without AI, making them effectively harmless.