Black October: why bugs discovered by OpenAI tech are creating a cyber emergency
Websites you use every day may have had security weaknesses that hackers could use for years. These hidden problems in website code were only recently found by artificial intelligence (AI).
Why it matters: The programming language PHP runs millions of websites. The security flaws could let hackers steal private information or take control of the computers that run affected websites.
If hackers used these flaws, they could steal sensitive information, such as passwords and personal data, or take control of vulnerable servers, which are computers that run websites.
Driving the news: On Wednesday, a possible attack using weaknesses in PHP was reported. This led governments and companies to temporarily take their websites offline while they installed security fixes.
Dozens of websites in the U.S., U.K. and other parts of the world were briefly taken offline so their operators could install the fixes.
The disruption put the National Security Agency and Europe's cybersecurity agency on alert.
State of play: Security updates to fix the problems were released on Oct. 21, 2026. Cybersecurity companies urged everyone using PHP to install the updates right away.
What they're saying: OpenAI's technology helped find the flaws. OpenAI called the discovery "one of the most impactful security issues in recent memory," meaning one of the most serious security problems in recent years.
"To our knowledge, frontier AI found these vulnerabilities before attackers did," OpenAI said. Frontier AI means some of the most advanced AI technology available.
The cybersecurity company Wiz wrote in a blog post: "These findings rank among the most severe vulnerabilities discovered in PHP, and arguably in software history." Wiz said these security flaws were among the most serious ever found in PHP and possibly in any software.
What is PHP?
You may never have heard of PHP, even though you have probably used websites that rely on it for decades.
PHP stands for Hypertext Preprocessor. It is a programming language used by about 70% of websites that use a known language to run their servers.
PHP has been around since the 1990s. It helps build websites by handling information and creating content that is sent to your web browser.
PHP is still used by many kinds of websites today, including Wikipedia, WordPress blogs and online shopping sites.
How it works: HTML controls what you see on a website. PHP works behind the scenes to gather information and create the content that the website shows you.
What was the PHP vulnerability, exactly?
AI researchers found two serious security flaws in PHP. These flaws could have allowed someone to take control of a website's server without permission.
Hackers could use these flaws, which cybersecurity companies named "php2shell," to steal information from affected websites.
Between the lines: According to Wiz, the flaws had gone unnoticed for more than 10 years because using them required complicated technical work. AI helped researchers figure out how to do that.
Why cybersecurity incidents are a big deal
Thought bubble via Axios' Bradley Olson: The PHP flaws are so serious that the NSA warned website operators to take their sites offline if they did not have enough time to install the security fixes.
But the cybersecurity problems in recent days go far beyond PHP. They include disruptions to platforms used by software developers, data leaks involving public schools, break-ins at publicly traded companies and other incidents.
A major Axios report also found that banks were detecting outside AI agents accessing customer accounts without permission. Banks are working quickly to stop this problem.
Cybersecurity experts are calling this series of attacks "Black October" because there have been so many incidents and the risks are so serious. So far, however, many organizations have reduced the risks and prevented major real-world harm.
Security experts and AI companies have warned for months that a wave of serious cyber emergencies was likely to arrive soon. They have also been working to protect lesser-known software that still supports much of the modern internet.
The bottom line: As attacks continue, experts have urged people to protect their passwords, use a password manager and avoid panicking.
To understand how much harm a cyber emergency has caused, experts look at how far the damage spreads into everyday life. Past examples include ransomware attacks that took hospital software offline and an attack on a pipeline system that briefly disrupted fuel supplies on the U.S. East Coast.