AI Finds Flaws in Code Behind 70% of Websites

An estimated 70% of the internet runs on PHP, and for the past two years, a dangerous flaw inside that language has sat unresolved by human developers. That changed on Oct. 21, when OpenAI announced that researchers working under its Patch the Planet cybersecurity program used its GPT-5.6 Sol model to uncover critical vulnerabilities in the programming language. The company said it then coordinated researchers, PHP maintainers, security providers, and government cybersecurity agencies to fix the issues over a two-month period. OpenAI attributed the lengthy timeline to the task's complexity, which required major changes to the PHP engine.

The PHP Foundation has released patched versions 8.2.35, 8.3.36, 8.4.27, and 8.5.12 to address the vulnerabilities. PHP 8.1 and older versions will not receive official fixes. The coordinated release was originally scheduled for Oct. 22 but was moved up 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 company highlights the incident as an example of what it calls the Defender's Window concept, a critical, narrow timeframe during which organizations can use advanced frontier AI models to find, patch, and strengthen their cybersecurity defenses before those same AI-driven attack capabilities become widely available to malicious threat actors. OpenAI introduced this concept after its models hacked Hugging Face.

Operating as part of the Patch the Planet program, researchers from Calif, a California-based cybersecurity firm and the program's founding partner, began auditing PHP with OpenAI tools on July 30, 2026, at the PHP Foundation's request. The Foundation had known about the underlying flaw since 2024 but couldn't identify an exploitation method or a fix. Calif researcher Ryan A. first identified the exploitable vulnerability on Aug. 11, followed by OpenAI researchers that same day. Subsequently, another cybersecurity firm, Wiz, independently identified an additional vulnerability. 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. 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. The company is challenging a view that the flaws would never have been exploitable without AI, making them effectively harmless. OpenAI argues that powerful, revolutionary technology will inevitably be used by bad actors, and that it is a collective responsibility to act proactively to address any potential exploitable flaws. Anthropic's Claude Mythos recently identified 'thousands of zero-day vulnerabilities' in 'every major operating system and every major web browser.'

The PHP Foundation has released patched versions, and OpenAI says every site using PHP can now safely upgrade to stay secure. No further action has been announced as of Oct. 22, and it remains to be seen how many sites will update their versions in the coming weeks.