The vulnerabilities, known together as PHP2Shell and tracked as CVE-2026-109618 and CVE-2026-109619, each carry a severity rating of 9.2 and stem from how PHP handles memory.
They could let an unauthenticated attacker run malicious code on a vulnerable server or read sensitive data from memory, including passwords, tokens and API keys.
OpenAI says it led a coalition of maintainers, researchers and security providers on the response.
It says the security firm Calif found the bugs using OpenAI's GPT-5.6 Sol model, while Wiz independently found and reported the same flaws.
Wiz says PHP powers 70 percent of websites, including WordPress, Drupal, Joomla and Wikipedia's MediaWiki, and that every version from the past decade, back to 5.4, is affected by at least one of the bugs.
Because the problem sits in PHP's core engine, even a basic "Hello World" app can be vulnerable regardless of how carefully its own code is written.
Amazon Web Services says a honeypot, a decoy system built to attract attackers, logged an exploitation attempt on October 17, four days before fixes were public.
AWS security chief CJ Moses says the flaws are now "broadly exploited in the wild," though it is unclear how the attacker got details during the embargo or whether the attempts would have worked on real systems.
Cloudflare CEO Matthew Prince says attempts rose from thousands to millions after the announcement.
Many sites went dark as a precaution. The UK's National Cyber Security Centre and the U.S. National Security Agency urged operators to update, and the NSA advised taking systems offline if they cannot be patched immediately. Wikipedia pulled some systems offline, and sites for the BBC, Dutch Parliament and several governments went down, as did Irish retailer Woodie's, the Journal and the Finnish government's land registry records. It is not yet clear whether any were compromised. Wiz says the flaws existed for more than a decade, and that AI models made it practical to chain several bugs into working exploits and adapt them to different targets in hours, work it says once took a world-class team months. It says the PHP patch fixes the underlying problem in the patched release, and that Cloudflare, AWS, Google and Microsoft helped prepare mitigations for those who cannot update right away. Separately, GitLab released fixes on October 21 for a maximum-severity 10.0 flaw that could allow code execution on self-managed servers, with no workaround and no reported attacks. The curl project will begin handling low and medium-severity reports publicly from October 26, citing an "avalanche" of submissions.