Wiz Research disclosed PHP2Shell on October 21, a set of memory-safety bugs in the core PHP interpreter grouped under CVE-2026-109618 and CVE-2026-109619, with severity reaching CVSS 9.2. Wiz describes four distinct bugs. The most serious is a use-after-free in the upload-progress unserializer that yields pre-authentication remote code execution, demonstrated against stock WordPress, Drupal and Joomla containers. The same CVE covers a remote process-memory disclosure that works even when the application never calls session_start. The second CVE covers a use-after-free in fatal-error backtrace handling, shown to give code execution on Drupal, and an OPcache type confusion shown to give code execution on WordPress. Wiz says nearly every PHP release back to 5.4 is affected, and that even a trivial Hello World application running on a vulnerable interpreter can be exposed, because the bugs sit below the application layer.
The AI angle is what turned a bad week into an unusual one. Wiz says the bugs were found with its own Atlas system alongside Gemini 4 Argon and GPT-5.6 Sol. Separately, Calif, working inside OpenAI's Patch the Planet program, found one of the flaws with GPT-5.6 Sol. The timeline runs from discovery on August 19 to a report to the PHP project on August 24 and acknowledgment on September 21. A Hacker News post leaked details on Tuesday and was taken down, and PHP moved its fix release forward by a day to October 21.
The response was correspondingly large. NSA, FBI and CISA urged administrators to patch immediately or take systems offline if they cannot. Palo Alto Unit 42 counted more than 22.6 million internet-exposed instances that may be vulnerable, and France, Denmark, Finland and the Netherlands took some government sites offline. CISA said it had not observed exploitation at publication, and OpenAI said it knew of none in the wild. Linux distributions and long-term-support users need vendor backports, and PHP 8.1 and older are already out of support.
Two caveats matter. The widely quoted seventy percent figure is PHP's share of websites whose server language can be identified, not a count of exposed hosts. And Wiz itself expects untracked variants of these bug classes to exist, which means the patch closes the known paths rather than the whole surface. The broader significance is that this is one of the clearest public cases of frontier models finding deep, long-lived bugs in foundational infrastructure, and the speed of the leak shows how short the window between AI-assisted discovery and public exploitability has become.
- Wiz frames this as a set of bug classes and expects untracked variants; Defense One stresses the 22.6 million exposed instances and federal patch-or-offline guidance.
- TechCrunch and Semafor lead with the AI discovery story, quoting Wiz that humans probably would not have found it; TechCrunch dates exposure to PHP 5, Wiz to 5.4.
- The Information's commentary argues the 'defenders window' is closing: the same models that found the bugs make exploitation faster once details leak.