Cloudflare has announced that it successfully mitigated the largest volumetric distributed denial-of-service (DDoS) attack ever recorded. The attack peaked at 11.5 terabits per second (Tbps) and was automatically blocked by the company’s defenses.
The incident happened recently and lasted only about 35 seconds. According to Cloudflare, the attack was a UDP flood that originated mainly from Google Cloud servers. Even in that short duration, the scale of the attack made it one of the most significant in Internet history.
This new record comes just two months after Cloudflare handled another massive 7.3 Tbps DDoS attack in June. Before that, the previous high was 3.8 Tbps in October 2024. Microsoft has also faced similar large-scale threats, including a 3.47 Tbps attack against an Azure customer in January 2022, and another attack that disrupted multiple Microsoft 365 and Azure services in July 2024.
Cloudflare highlighted that its systems have been handling a rising number of such attacks. The company’s Q1 2025 DDoS report showed a 358% year-over-year increase in attacks, with over 21 million DDoS events mitigated in 2024. Many of these were multi-vector campaigns involving SYN floods, SSDP amplification, and Mirai-based botnets.
DDoS attacks aim to overwhelm servers or networks with massive volumes of data, making them inaccessible to legitimate users. The rapid growth in attack scale underlines how attackers are increasingly using cloud resources and botnets to amplify their campaigns.
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