Cloudflare blocked a record 11.5 Tbps DDoS attack

Cloudflare blocked what it called the largest ever DDoS attack, peaking at 11.5 Tbps, described as a UDP flood that mainly originated from Google Cloud and occurred during weeks-long assault waves. According to Cloudflare, the defence systems automatically blocked hundreds of hyper-volumetric DDoS attempts in the preceding weeks, with the 11.5 Tbps event lasting about 35 seconds.

The report notes that, in June, Cloudflare announced that during 2025 Q2 it had automatically blocked the largest ever reported DDoS attacks, with peaks of 7.3 Tbps and 4.8 billion packets per second. The 7.3 Tbps attack targeted a single IP and was multivector, comprising UDP floods alongside QOTD, Echo, NTP, Mirai, Portmap and RIPv1 attacks. The article frames the 11.5 Tbps incident as part of ongoing, record-setting activity in DDoS evolution, highlighting the speed and scale of today’s internet-scale floods.