Anthropic unreleased model chains multiple vulnerabilities into working Chrome, Safari, Windows and Linux exploit chains

Anthropic says one of its unreleased internal research models discovered multiple vulnerabilities in Chrome, Safari, Android, Windows and Linux in experiments and chained them into working proof-of-concept exploit chains; all vulnerabilities were reported to vendors first and have been fixed, and none have been seen in real attacks. An Anthropic Frontier Red Team article lists five chains: the Chrome chain uses four vulnerabilities to go from visiting a webpage to code execution outside the sandbox, fixed in Chrome 156; the Safari chain runs no code and, after disabling the same-origin policy, can read the user's login data on other websites, fixed in iOS and iPadOS 26.5.2; the Windows chain is a denial of service against a server responding to HTTP/3 requests (CVE-2026-33096); the Linux chain obtains a root shell without logging in when the target runs a multipath TCP listener (CVE-2026-98432).