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Automatic Key Exchange: faster, post-quantum secure origin handshakes for 45 billion daily connections (and counting)

Cloudflare's Automatic Key Exchange probes origins to lead with preferred key exchange, cutting HelloRetryRequests from 52% to 3.7% and enabling automatic post-quantum origin connections.

Cloudflare announced Automatic Key Exchange, an extension of Automatic SSL/TLS that probes each origin's supported key agreement algorithms and leads with the preferred one, favoring the post-quantum hybrid X25519MLKEM768. Rollover across roughly 45 billion daily origin connections cut HelloRetryRequests from about 52% to 3.7%, saving more than 150 ms of p90 handshake latency. Hundreds of thousands of domains now receive post-quantum origin connections without manual configuration, supporting Cloudflare's goal of quantum-safe encryption by 2029 to counter harvest-now-decrypt-later attacks.

Cloudflare Blog · 8d agoResearch

CDN Tsunami Attack Abuses HTTP/3 Translation for Up to 350x DoS Amplification

Researchers disclosed two DoS attacks exploiting CDNs' HTTP/3-to-HTTP/1.1 translation to amplify low-bandwidth requests up to 350x against origin servers.

Researchers named the two techniques HTTP/3 Bandwidth Amplification (HBA) and HTTP/3 Connection Amplification (HCA), exploiting the gap where CDNs speak HTTP/3 to browsers but only HTTP/1.1 to origins. All six tested CDNs (Alibaba, Baidu, Cloudflare, CloudFront, Fastly, Tencent) were susceptible to HBA, and five to HCA, with Cloudflare immune to HCA because it buffers full requests before opening backend connections. Attackers using under 5 Mbps forced over 100 Mbps at origins, and the 350x factor applies only to Alibaba, Baidu, and Tencent, which support the QPACK dynamic table. Testing identified 42,330 potentially vulnerable subdomains out of 151,685 hosted on the six providers across the Tranco Top 1M.

The Hacker News · 27d agoResearch

A revisit of remote Spectre attacks on Cloudflare Workers

Cloudflare details its 2024-2025 reassessment of remote Spectre attacks on Workers, covering new attack primitives and hardened defenses.

Cloudflare reassessed the feasibility of remote Spectre attacks against its Workers serverless infrastructure across 2024 and 2025. The write-up describes new attack primitives including Spectre gadgets, remote timers, and techniques for achieving co-location with victim workloads. It also explains new defenses that further harden Cloudflare Workers against speculative-execution side channels.

Cloudflare Blog · 28d agoResearch

Cloudflare DDoS Threat Report H1 2026: 1 Tbps attacks soar as DNS floods and geopolitical tensions drive a new wave

Cloudflare's H1 2026 report records a 519% surge in hyper-volumetric DDoS attacks, driven by DNS and CLDAP reflection amid geopolitical tensions.

Cloudflare detected a 519% surge in hyper-volumetric DDoS attacks across its network during the first half of 2026. Attack traffic was driven heavily by DNS and CLDAP reflection vectors, with 1 Tbps attacks becoming far more common. The report attributes reshaped attack patterns to major geopolitical conflicts.

Cloudflare Blog · Aug 11, 2026Research

Risky Bulletin: Academics find source code overlaps between Geedge and China's Great Firewall

Academics linked Chinese vendor Geedge Networks' Tiangou Secure Gateway source code to one of the Great Firewall's three traffic filtering capabilities.

US researchers presenting at USENIX Security reconstructed Geedge Networks' Tiangou Secure Gateway firmware from over 100,000 leaked files, including Git repositories with commit history, and matched its filtering behavior to sections of China's Great Firewall. They found only 1 of 3 characterized DNS injectors matched Geedge code, noted the system relies on memory-unsafe C components and copied third-party code, and said its bugs could aid future circumvention tools. Geedge also exports censorship tools to Kazakhstan, Ethiopia, Pakistan, and Myanmar. The newsletter additionally rounds up multiple breaches.

Risky Business News · 26d agoResearch2

BGP Role model: tracking the adoption of RFC 9234

Cloudflare measured RFC 9234 adoption, finding BGP Role deployment growing but two Tier 1 networks unexpectedly stripping the Only to Customer attribute.

Cloudflare analyzed adoption of RFC 9234, which introduces BGP Roles and the Only to Customer (OTC) attribute allowing routers to reject route leaks on their own. The measurement study assessed who has deployed the mechanism in the global routing table. It found two Tier 1 networks unexpectedly stripping OTC attributes, which could undermine leak protection.

Cloudflare Blog · 29d agoResearch

terms.txt: A Consent and Compensation Protocol for Agentic Web Access

terms.txt specifies a robots.txt-style protocol for per-path, per-purpose AI crawler consent and compensation, with enforcement adding 0.20-0.65 ms per request.

The paper documents that automated clients now make up most web requests, that training dominates Cloudflare-classified crawling, and that the largest AI platforms fetch thousands of pages per returned visitor while robots.txt cannot express identity, purpose, terms, or price. It specifies terms.txt plus an origin-enforced exchange using Web Bot Auth signatures, signed intent, delegation tokens, HTTP 402 negotiation, and signed receipts. A dependency-free implementation adds 0.20 to 0.65 ms per request on one vCPU.

arXiv cs.CR · 6d agoResearch