Threat Bulletin 1331: credential stuffing against a developer platform platform in the UK

On Wednesday 1 April 2026 at 08:22 UTC, a credential stuffing targeted a developer platform customer in the UK. The attack peaked at 118.4 million requests per second and lasted 54 minutes. Traffic originated from 2133 autonomous systems in 22 countries, predominantly compromised cloud VMs.

Vector credential stuffing
Peak 118.4 million requests per second
Duration 54 min
Time to mitigation 0.911 s
Attack traffic reaching origin 0.053%
Legitimate traffic challenged 0.69%

Timeline

The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 716 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

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

Recommendations

  • Add a dedicated rate limit for the targeted route.
  • Enable log streaming to your SIEM for faster correlation.
  • Keep origin IPs out of public DNS history.

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