AI agent incident
AI models helped researchers find PHP2Shell, two critical remote code execution flaws in PHP itself
What happened
Two flaws in the PHP engine, CVE-2026-109618 and CVE-2026-109619, rated 9.2 on CVSS v4.0, let an unauthenticated web request run code on servers that use PHP to serve pages. They were found with the help of frontier AI models. Calif's Ryan Austin says an LLM agent reviewing PHP's source spotted the faulty code, and an LLM then turned the pattern into a reusable skill that found more variants; Wiz says it used Gemini 4 Argon and GPT-5.6 Sol to find the first bug on August 19 and to build and validate exploits; the CVE record credits OpenAI as finder. The CVE numbers leaked on October 20 and PHP moved its fix forward a day, releasing 8.5.12, 8.4.27, 8.3.36 and 8.2.35 on October 21; PHP 8.1 and older get no official release. Amazon logged one exploitation attempt on October 17, four days before disclosure, and security firms reported attempts after the patch. As of October 22 no successful compromise had been confirmed and neither flaw was in CISA's catalog of known exploited vulnerabilities.
Why it matters
AI-assisted source review found two critical bugs in one of the most widely deployed codebases on the web, and by Wiz's account the models also helped turn them into working exploits. AI shortened the embargo as well: Chainguard's chief executive told The Register his team rediscovered the bugs with an AI harness and a frontier model after hearing only that something was coming, and the PHP Foundation says Chainguard broke the embargo by publishing patched images before the release. Plan for fixes measured in hours, hunt from the earliest attempt rather than the disclosure date, and decide in advance what happens to hosts on unsupported versions, which CISA says to take offline until they can be patched.
Sources
- php.net PHP security advisory: Critical remote code execution vulnerabilities, update now
- GitHub RCE via OOM corruption (GHSA-w8hw-w9fx-j79w)
- cve.org CVE-2026-109618
- calif.io php2shell
- wiz.io PHP2Shell: AI uncovers critical RCE vulnerabilities affecting 70% of the Internet
- thephp.foundation Today's PHP Security Release, and How We're Strengthening PHP Security
- aws.amazon.com Amazon Threat Intelligence identifies PHP2Shell exploitation prior to public disclosure in MadPot
- CISA Critical Vulnerabilities in PHP Require Immediate Patching
- The Register PHP blames supply chain security biz Chainguard for putting entire web at risk
- The Hacker News PHP2Shell: Two Unpatched Critical PHP RCE Flaws (CVSS 9.2) Trigger Emergency Security Alert
- The Hacker News PHP2Shell: What Actually Protects You Before the 14:00 UTC PHP RCE Patch, and What Doesn't
- SecurityWeek PHP2Shell: Mass Exploitation Looms for Leaked Critical PHP Flaws
- CyberScoop PHP releases emergency fixes for 2 critical vulnerabilities
- Cybersecurity Dive Critical PHP vulnerabilities expose vast majority of websites to potential compromise