By Leo Marchandon
Oct 21 (Reuters) - Government websites across Europe went dark on Wednesday as operators raced to patch two critical vulnerabilities in PHP, one of the most widely used programming languages on the web.
The developers of PHP said on Wednesday they would release patches for two critical vulnerabilities, and EU cybersecurity officials warned organisations unable to apply the fixes to take affected websites offline. Here is what you need to know:
WHAT IS PHP?
PHP is a programming language
that runs websites. It works behind the scenes. When a user loads a page, the server running PHP assembles the content and sends the finished page to the browser.
It is free, open source and maintained by volunteers. Site owners rarely interact with it directly.
PHP runs nearly 70% of all websites whose programming language can be identified, according to web technology tracker W3Techs. It is the engine behind WordPress, the software that powers about 40% of all websites such as blogs, small business pages, government portals, online shops and news sites.
WHAT ARE THE RISKS OF THE FLAWS?
The two vulnerabilities are rated 9.2 out of 10 on the CVSS v4.0 severity scale, a standard industry scoring system. CERT-EU, the European Union's cybersecurity response team, said that rating signals unauthenticated remote code execution, meaning an attacker can run commands on a vulnerable server, over the internet, with no password or account.
A single flaw in PHP opens the same door on millions of servers at once. Whoever exploits the flaw controls the website. GoDaddy, a web hosting provider, said that could mean stolen data, defaced pages or full-system compromise. Cloudflare's chief technology officer said early attacks were emerging.
Most small websites are typically run by owners with no security staff, often on shared hosting where they do not manage the server and may not know who updates PHP. Wordfence, a security plugin for WordPress sites, warned that the usual automatic updates will not apply this fix. CERT-EU's guidance is to take affected sites offline rather than leave them exposed.
HOW WAS IT FOUND?
Researchers at security firm Calif, working with OpenAI, reported the first flaw to PHP on August 11 after finding it with OpenAI's GPT-5.6 Sol model, the company said. Wiz, a security firm owned by Alphabet's Google, found the flaws independently and reported a second one on August 24, also using AI models.
Wiz said the findings "rank among the most severe vulnerabilities discovered in PHP, and arguably in software history." The underlying flaws had been present for decades, the firm said, but proving they were exploitable required a chain of steps "at the edge of what human researchers could practically achieve."
US President Donald Trump's administration said it was "tracking and coordinating with federal agencies and leading SI labs to expedite the release of the fix," referring to Trump's preferred name for artificial intelligence. It framed the discovery as evidence that American "Super Intelligence" strengthens national security.
(Reporting by Leo Marchandon in GdanskEditing by Bill Berkrot)
