Cloudflare blocks largest recorded DDoS attack peaking at 11.5 Tbps

Cloudflare disclosed blocking a record 11.5 Tbps volumetric DDoS attack (with peaks of 5.1 Bpps), later clarifying the traffic originated from a mix of IoT and cloud providers rather than primarily Google Cloud, and contextualized the event alongside prior record attacks (including 7.3 Tbps in June and Microsoft’s 3.47 Tbps in 2022). The company’s 2025 Q1 DDoS Report highlights steep growth in network-layer attacks (509% YoY), 21.3 million attacks mitigated in 2024, and an 18-day multi-vector campaign leveraging SYN floods, Mirai-driven botnets, and SSDP amplification.