Researchers have found severe security flaws in PHP, the open-source scripting language behind about 70% of the world’s websites. They found them with help from an OpenAI model.
The vulnerabilities, collectively dubbed PHP2Shell, have been described as potentially among PHP’s most severe in over a decade. Some have compared the episode to Heartbleed.
What the researchers found
The flaws surfaced during an audit carried out in August 2026 by researchers at Calif, a security firm. The team used GPT-5.6 Sol, one of OpenAI’s models, to comb through PHP’s code. Ryan Austin of Calif is credited with discovering the vulnerabilities.
The bugs allow remote code execution and control over server memory. Put simply, an attacker sitting anywhere on the internet could make a server run instructions it was never supposed to run.
According to the research findings, the flaws could expose sensitive data belonging to site visitors. They could also serve as a foothold for further cyber attacks against other systems.
How the disclosure unfolded
Calif CEO Thai Duong alerted Volker Dusch, who works on PHP, on August 11. That started a quiet, coordinated effort to fix the problem before attackers could learn about it.
The response pulled in PHP maintainers, outside researchers, security providers, and US agencies including CISA and ONCD.
OpenAI announced its ‘Patch the Planet’ initiative on October 21, 2026. The program is designed to mobilize defenders around the PHP2Shell vulnerabilities.
A partial leak of information about the flaws forced the team to expedite the patch release to October 22.
As part of the effort, OpenAI is contributing $1 billion in subsidized model access. The goal is to put AI tools into the hands of frontline defenders working on vulnerabilities like these.
Why AI-assisted bug hunting changes the picture
Experts quoted in the research drew the obvious parallel to Heartbleed. They also stressed that AI-enhanced vulnerability discovery cuts both ways. The same capability that helps defenders spot holes could help attackers find and exploit them.
That tension sits at the center of OpenAI’s $1 billion pledge. If models can surface critical flaws faster, the race becomes about who uses them first. Subsidizing access for defenders is an attempt to tilt that race toward the people doing the patching.
What this means
For website operators, the immediate priority is simple: update. A patch exists, and the partial leak means the clock started ticking before anyone wanted it to.
For the open-source world, PHP2Shell is another reminder of a structural problem. Critical internet infrastructure often rests on projects maintained by small teams. The heavy involvement of US agencies in this disclosure shows how seriously governments now treat that dependency.
What to watch next: how quickly sites apply the October 22 patch, whether any exploitation of PHP2Shell is reported in the wild, and how OpenAI distributes its $1 billion in subsidized access.
Disclosure: This article was edited by Diego Almada Lopez. For more information on how we create and review content, see our Editorial Policy.