Frontier AI models helped uncover PHP2Shell, two critical flaws in the PHP engine behind roughly 70% of websites, and the scramble to patch them shows how fast AI is shrinking the time defenders get to react.
PHP shipped fixes on October 21 in versions 8.5.12, 8.4.27, 8.3.36 and 8.2.35, and urged all users to update immediately. The two bugs, CVE-2026-109618 and CVE-2026-109619, are both rated 9.2 under CVSS v4.0 and can allow unauthenticated remote code execution.
How AI found it
Volgens OpenAI, security firm Calif identified one of the flaws using GPT-5.6 Sol through OpenAI’s Patch the Planet programme, while Wiz independently found and reported both. Wiz says it used its own tooling alongside Gemini 4 Argon and GPT-5.6 Sol, and demonstrated unauthenticated code execution on WordPress, Drupal and Joomla.
Wiz says every PHP version released in the last decade, back to 5.4, is affected by at least one of the bugs. Exploiting them required a chain of steps “at the edge of what human researchers could practically achieve,” and frontier models “substantially reduced that barrier.”
The embargo didn’t hold
The coordinated release was planned for October 22. As TechTarget reports, CVE IDs started circulating on forums on October 20, so PHP brought the release forward a day. Distributor Chainguard then published patched images hours early, a move the PHP Foundation criticised and Chainguard’s CEO defended, citing reports of active exploitation.
Amazon says its honeypots picked up exploitation attempts as early as October 17. Cloudflare CEO Matthew Prince said attempts across its network reached “millions” after the announcement.
OpenAI’s proposed playbook
OpenAI used the episode to propose a five-stage response for AI-found bugs that hit many products at once: validate and fix the flaw (including testing the patch against frontier models), give affected organisations time to act, coordinate with government partners, prepare updates across products, then publish guidance.
It says these bugs are among several significant vulnerabilities it has already found, and it expects similar findings “to increase sharply in the coming months.”
Why it matters
Researchers have shown LLM agents can exploit known vulnerabilities for a while. PHP2Shell is that capability at internet scale, and it lands the same week OpenAI disclosed that its own coding agents weakened safety monitoring.
If models can find and weaponise bugs this quickly, long embargoes look fragile. For anyone running PHP, including WordPress sites, the advice is simple: update the PHP runtime and restart every worker. Updating your app alone doesn’t patch the PHP underneath it.
