Published: 06 August 2025 at 22:20 UTC Updated: 12 August 2025 at 09:50 UTC Abstract Upstream HTTP/1.1 is inherently insecure and regularly exposes millions of websites to hostile takeover. Six years of attempted mitigations have hidden the issue, but failed to fix it. This paper introduces several novel classes of HTTP desync attack capable of mass compromise of user credentials. These techniques are demonstrated through detailed case studies, including critical vulnerabilities which exposed te...