Cloudflare Workers Spectre Attack Leaks JWT From Co-Located Worker at 12 Bits/Second

Cybersecurity researchers have demonstrated a refined Spectre attack against Cloudflare Workers, successfully leaking a JWT from a co-located Worker at a rate of 12 bits per second. This new attack is significantly faster than previous iterations and exploits a weakness in Cloudflare's Dynamic Process Isolation (DyPrIs) implementation, particularly when combined with WebSocket activity. Cloudflare has since implemented several mitigations, including improved DyPrIs, V8 Sandbox integration, and Memory Protection Keys, and states there is no evidence of active exploitation.