Threat Bulletin 1453: cache-busting query flood against a airline booking platform in Western Europe

On Saturday 19 September 2026 at 10:25 UTC, a cache-busting query flood targeted a airline booking customer in Western Europe. The attack peaked at 33.7 million requests per second and lasted 30 minutes. Traffic originated from 545 autonomous systems in 28 countries, predominantly mobile carrier ranges.

Vector cache-busting query flood
Peak 33.7 million requests per second
Duration 30 min
Time to mitigation 0.194 s
Attack traffic reaching origin 0.058%
Legitimate traffic challenged 0.45%

Timeline

The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 370 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

A brief increase in p99 latency of 84 ms during the first minute, then normal service.

Recommendations

  • Enable authenticated origin pulls.
  • Review allow-listed partner ranges quarterly.
  • Add a dedicated rate limit for the targeted route.

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