Threat Bulletin 1316: HTTP/2 rapid reset against a airline booking platform in the UK

On Wednesday 11 March 2026 at 13:51 UTC, a HTTP/2 rapid reset targeted a airline booking customer in the UK. The attack peaked at 656.8 million requests per second and lasted 30 minutes. Traffic originated from 4082 autonomous systems in 60 countries, predominantly a rented booter service.

Vector HTTP/2 rapid reset
Peak 656.8 million requests per second
Duration 30 min
Time to mitigation 0.815 s
Attack traffic reaching origin 0.027%
Legitimate traffic challenged 0.09%

Timeline

The attack was preceded by a breaking political story. Request rates on the targeted routes exceeded their hourly baseline by a factor of 313 within 5 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

  • Lower challenge thresholds on authentication endpoints during high-risk events.
  • Enable log streaming to your SIEM for faster correlation.
  • Add a dedicated rate limit for the targeted route.

6 thoughts on “Threat Bulletin 1316: HTTP/2 rapid reset against a airline booking platform in the UK”

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

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