AI-Found PHP2Shell Flaws Knock Websites Offline Worldwide

Estimated reading time: 7 minutes · Last updated: 24 October 2026

PHP2Shell is a pair of critical flaws in PHP, the programming language that runs 70% of the world's websites. Its public disclosure on Wednesday 21 October 2026 sent governments and companies scrambling. Teams at OpenAI, Google-owned Wiz and the security firm Calif used AI to work out how to exploit bugs that Wiz says sat in PHP's code for more than a decade. They then helped the PHP Foundation ship a fix. An attacker who succeeds could run their own code on a server, disrupt services or read memory holding passwords and customer data. Japanese airline ANA, Wikipedia's operator and UK government departments took services partly offline while patches went in. Cloudflare's chief executive reported millions of exploit attempts within days.

Think of a hotel room where you check out, but your key still works. And so you can just go back into that hotel room later, and now somebody else's stuff is there.

Patrick Fussell, global head of adversary simulation, IBM

How a Memory Bug in PHP Exposes Passwords and Servers

The weakness lies in how PHP manages a computer's memory. When a request to a website ends abruptly, PHP can leave fragments of data behind. Someone who knows where to look may later read, expose or corrupt that leftover memory.

Cloudflare, the web infrastructure provider, has worked on the problem with the PHP Foundation, Calif, OpenAI and Wiz. It says the consequences include remote code execution, which means an outsider running commands on the server. Disrupted services and leaked customer records are also possible. The memory an intruder reaches could contain passwords.

Patrick Fussell, global head of adversary simulation at IBM, compares it to a hotel guest whose key card keeps working after checkout. That guest can walk back in once a new guest's belongings are in the room. The PHP Foundation has published a patch and wants every site operator to install it without delay.

Both the US National Security Agency and ENISA, Europe's cybersecurity agency, issued advice telling organisations to act at once on the two flaws.

How AI Turned a Decade-Old Bug Into a Working Exploit

The bugs were not new. Wiz says they had hidden in PHP's codebase for more than a decade. Turning them into a working attack required a chain of steps so intricate that Wiz placed it 'at the edge of what human researchers could practically achieve'.

AI closed that gap. An exploit is the working method an attacker uses to take advantage of a flaw. Researchers used models to adapt known exploitation techniques and to analyse what came back. Wiz named its tools as Google's Gemini 4 Argon, Wiz Atlas and OpenAI's GPT-5.6 Sol.

In a blog post on 21 October, Wiz researchers wrote that 'with frontier AI models and the right tools, a single researcher completed in a week what previously would have taken a world-class team months of work.' Describing the episode as an AI inflection point, Wiz said PHP served as the 'backbone of the web'.

The flaws were found in late August. The details stayed private until 21 October, after PHP had a fix ready, which gave defenders a patch on the same day attackers learned what to look for.

Governments, Banks and Wikipedia Pulled Services Offline

Japan's Prime Minister Sanae Takaichi went further than most leaders. She said companies should consider suspending services to cut their exposure. In a post on X on 21 October she urged operators to 'check if your publicly available websites use PHP, and prepare to apply the fix patch that will be released tonight… as soon as possible.'

ANA, railway operator JR West and the bank MUFG all reported pages and services temporarily suspended. In Europe, government sites in France, Denmark, Finland and the Netherlands came down while fixes were applied, and one of them belonged to the Dutch cyber security agency. Dutch Prime Minister Rob Jetten said his cabinet was 'closely monitoring the situation surrounding the vulnerabilities in PHP.'

In Britain, minister Elizabeth Lloyd told the House of Lords on Thursday 22 October that nearly three dozen government services were unavailable during the upgrades and four more were partially unavailable. The Wikimedia Foundation, which runs Wikipedia, took a number of its systems down as a precautionary measure, as first reported by CNN. The Irish news site The Journal also went offline briefly that morning to shore up its defences.

Attackers did not wait. Cloudflare's CEO said on X that the company's network had logged millions of exploit attempts over a couple of days.

Is PHP2Shell the Next Heartbleed?

Wiz researchers put the flaws in the same class as Heartbleed. Discovered in 2014, that bug struck encryption software that roughly two-thirds of the web was estimated to rely on, and it let criminals reach data that should have stayed protected. Wiz argues PHP2Shell could mark a similar turning point, because AI made long-dormant weaknesses practical to use.

Uneven patching is what Gang Wang expects. An associate professor at the University of Illinois, where he works in computer science, Wang points out that organisations will not all update at once. Now that the flaw is public, attackers have a window to go after the laggards, and AI lets them move faster.

Fussell agrees about the pace. He said 'the speed with which vulnerabilities are being discovered is well beyond what it ever was before.' He rejects the idea of a one-click server takeover, though. He said a real attack needs a couple of conditions that are 'fairly complex' and will not always line up for the person attempting it.

Nigel Green, CEO of the financial advisory firm deVere Group, framed the stakes for shoppers. He said utility portals, delivery apps, ticketing sites, subscription services, marketplaces and booking platforms could all keep card details on code of this kind.

Will the PHP2Shell fallout be contained?

The bottom line

The lasting significance of PHP2Shell may lie less in the bugs themselves than in who found them and how quickly. Flaws that went unnoticed for more than a decade became usable once Wiz, OpenAI and Calif pointed frontier models at them. Wiz says one researcher did in a week what once took a team months. Attackers have the same speed available to them, which helps explain why Cloudflare counted millions of exploit attempts within days of disclosure. The patch exists. What remains open is how many of the sites behind that 70% figure apply it before someone else finds the gap. Also unsettled is whether Fussell's caution about complex exploit conditions holds once more attackers try.

What to watch

• Watch how quickly website operators install the PHP Foundation's patch; Gang Wang expects uptake to be uneven, and no completion date has been set.
• Watch whether Cloudflare reports exploit attempts rising or falling from the millions seen in the first days after disclosure; no date for an update has been given.
• Watch for the UK government to restore the nearly three dozen services Elizabeth Lloyd described as unavailable; no date for their return has been set.