On Sunday 3 May 2026 at 09:33 UTC, a login endpoint flood targeted a tax authority portal customer in the UK. The attack peaked at 467.9 million requests per second and lasted 31 minutes. Traffic originated from 413 autonomous systems in 17 countries, predominantly misconfigured open reflectors.
| Vector | login endpoint flood |
| Peak | 467.9 million requests per second |
| Duration | 31 min |
| Time to mitigation | 0.338 s |
| Attack traffic reaching origin | 0.004% |
| Legitimate traffic challenged | 0.10% |
Timeline
The attack was preceded by a ransom note demanding payment in Monero. Request rates on the targeted routes exceeded their hourly baseline by a factor of 329 within 33 seconds. The risk score of participating clients crossed the challenge threshold automatically and proof-of-work difficulty rose with origin load.
What the customer saw
A brief increase in p99 latency of 219 ms during the first minute, then normal service.
Recommendations
- Enable authenticated origin pulls.
- Enable log streaming to your SIEM for faster correlation.
- Add a dedicated rate limit for the targeted route.
Any plans to support per-tenant limits keyed on a JWT claim?
Good question. We will cover that in a follow-up post.
The billing model is what got our finance team on board, honestly.
Thanks — sharing this with our on-call team.
We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.
Good question. We will cover that in a follow-up post.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.