Get Quartz in your inbox

Free daily briefing on global business news.

A 20-year-old bug nearly broke the internet

A decades-old PHP vulnerability forced major websites offline and exposed the growing threat of AI-powered cyberattacks

 Patrick Lux/Getty Images

A version of this article originally appeared in Quartz’s AI & Tech newsletter. Sign up here to get the latest AI & tech news, analysis and insights straight to your inbox.

Websites around the world went dark last week because of a flaw in code most people never think about. It sat inside PHP, software that runs an estimated 70% of all websites, including Wikipedia and WordPress.

Two bugs, that have been around for roughly 20 years, would have let a stranger take over a website’s server without a password. Researchers found them in August with the help of AI and spent weeks building a fix in secret. When it was released last Wednesday, agencies including the FBI and the National Security Agency warned that sites that couldn’t update right away might be better off going offline until they could.

Sites like 4chan, DeviantArt and the Internet Archive took the advice and went dark for hours or days, and government agencies in the Netherlands and........

© Quartz