Understanding the 'HTTP/2 Bomb' DoS Vulnerability and Its Impact
In June 2026, a critical denial-of-service (DoS) vulnerability known as 'HTTP/2 Bomb' was discovered, affecting major web servers including NGINX, Apache HTTP Server, Microsoft IIS, Envoy, and Cloudflare Pingora. This exploit combines HPACK compression amplification with Slowloris-style resource retention via HTTP/2 flow-control stalling, allowing a single attacker to exhaust tens of gigabytes of server memory within seconds, leading to rapid service disruption. The attack was identified by OpenAI's Codex under the guidance of security firm Calif, highlighting significant weaknesses in default HTTP/2 configurations. The disclosure of this vulnerability underscores the evolving sophistication of DoS attacks and the critical need for organizations to promptly update their web server configurations and apply available patches. With proof-of-concept exploits already published, the urgency for mitigation is heightened to prevent potential widespread service outages.
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