The Ghost in the Cloud: Spectre Vulnerability Pierces Cloudflare Workers

Cybersecurity researchers successfully executed a remote Spectre-style attack on Cloudflare Workers, demonstrating a cross-worker data leak in a live production environment. By exploiting speculative execution vulnerabilities in modern CPUs, the team managed to extract a JSON Web Token (JWT) from a separate, co-located worker at a rate of 12 bits per second. This discovery underscores the persistent challenges of maintaining strict isolation in multi-tenant serverless architectures, though Cloudflare has since reported that the specific vulnerability has been mitigated to protect user data.