Governments and companies around the world shut down websites Thursday as they raced to protect themselves from hacks after artificial intelligence uncovered critical flaws in a widely used programming language called PHP.

PHP helps run about 70 percent of the world's websites -- from online stores and news outlets to government services -- according to Wiz Research, one of the cybersecurity firms that found the two flaws.

Created in the early 1990s, PHP originally stood for "personal home page" but now means "hypertext preprocessor" and sits underneath popular web design platforms.

"These findings rank among the most severe vulnerabilities discovered in PHP, and arguably in software history," a Wiz blog post said.

Increasingly powerful AI models can spot weak points in back-end computer code that have gone unnoticed by humans for years.

That has heightened cybersecurity fears, with the number of...