Threat Bulletin 1371: HTTP/2 rapid reset against a airline booking platform in Western Europe

On Tuesday 26 May 2026 at 15:44 UTC, a HTTP/2 rapid reset targeted a airline booking customer in Western Europe. The attack peaked at 627.6 million requests per second and lasted 122 minutes. Traffic originated from 3281 autonomous systems in 100 countries, predominantly a headless-browser farm.

Vector HTTP/2 rapid reset
Peak 627.6 million requests per second
Duration 122 min
Time to mitigation 0.591 s
Attack traffic reaching origin 0.083%
Legitimate traffic challenged 0.21%

Timeline

The attack was preceded by a publicly announced sales event. Request rates on the targeted routes exceeded their hourly baseline by a factor of 272 within 27 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

The customer’s status page stayed green throughout; they learned about the attack from our notification.

Recommendations

  • Enable authenticated origin pulls.
  • Keep origin IPs out of public DNS history.
  • Enable log streaming to your SIEM for faster correlation.

10 thoughts on “Threat Bulletin 1371: HTTP/2 rapid reset against a airline booking platform in Western Europe”

  1. Quentin Becker

    We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.

  2. Elena Eriksen

    We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.

  3. We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.

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