Cloudflare Blocked the Most Powerful DDoS Attack in History — 11.5 Tbps

The record for the most powerful distributed denial-of-service (DDoS) attack, set in June 2025, has already been surpassed. Cloudflare announced that it recently mitigated the largest attack ever recorded, peaking at 11.5 terabits per second (Tbps).

The Attack

“Cloudflare’s defense systems operate without interruption. Over the past few weeks, we have blocked hundreds of hyper-volumetric DDoS attacks, the largest of which reached a peak power of 5.1 billion packets per second and 11.5 Tbps,” the company reported.

The assault was a UDP flood launched from multiple sources, including cloud and IoT providers—one of which was Google Cloud. Cloudflare said it would publish a detailed technical report on the incident soon.

Telemetry shared by the company suggests the record-breaking attack lasted only 35 seconds.

Previous Records

The new record dwarfs one set just two months earlier. In June 2025, Cloudflare stopped a 7.3 Tbps attack targeting an unnamed hosting provider. That incident was already 12% larger than the record set in January 2025 at 5.6 Tbps.

During the June attack, experts estimated that 37.4 terabytes of data were transmitted in just 45 seconds—the equivalent of streaming 7,500 hours of HD video or transferring 12.5 million JPEG photos.

Broader Context

The surge in attack power reflects the continued escalation of DDoS threats. In its Q1 2025 report, Cloudflare disclosed that over the previous year it mitigated 21.3 million DDoS attacks against customers, in addition to more than 6.6 million attacks on its own infrastructure.