By some accounts, up to 70 percent of websites use PHP in some capacity. It powers Wikipedia, WordPress, Drupal, and a host of other popular sites and platforms, including DeviantArt and 4Chan, which were temporarily shut down after the vulnerabilities were disclosed. Even governments weren’t immune.

But it’s not as simple as updating a few servers. The vulnerability exists in every version of PHP dating back roughly 20 years, many of which are no longer supported. That means some older sites and services that are no longer actively maintained are at risk, leaving them with little option but to permanently shut down.

Here’s all the latest developments in what security firm Wiz has called “among the most severe vulnerabilities discovered … in software history.”