On Wednesday 16 September 2026 at 13:07 UTC, a login endpoint flood targeted a municipal services customer in North America. The attack peaked at 921.5 million requests per second and lasted 108 minutes. Traffic originated from 2434 autonomous systems in 86 countries, predominantly a headless-browser farm.
| Vector | login endpoint flood |
| Peak | 921.5 million requests per second |
| Duration | 108 min |
| Time to mitigation | 0.391 s |
| Attack traffic reaching origin | 0.036% |
| Legitimate traffic challenged | 0.41% |
Timeline
The attack was preceded by a breaking political story. Request rates on the targeted routes exceeded their hourly baseline by a factor of 321 within 8 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
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Keep origin IPs out of public DNS history.
- Enable log streaming to your SIEM for faster correlation.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
Good question. We will cover that in a follow-up post.
How does the proof-of-work challenge behave on older Android devices? Any numbers below Android 10?
Any plans to support per-tenant limits keyed on a JWT claim?
Nice to read a vendor blog that admits what went wrong.
Great to hear, thanks for sharing your experience.
Nice to read a vendor blog that admits what went wrong.
Solid runbook advice. The DNS-at-2am point hit home.