A circuit breaker is a resilience pattern in software that stops sending requests to a failing service after repeated errors or timeouts. Instead of letting every caller keep retrying and amplifying the failure, the breaker “opens” for a period, fails fast, and then tests the service again later. This protects systems from cascading outages and keeps one degraded dependency from dragging down the rest of the environment.
In cyber security, circuit breakers matter because availability is part of defense. During an outage, an overloaded login, API, or AI service can produce bursts of retries, alerts, and stuck workflows that look noisy and unstable. A breaker reduces that pressure and helps teams distinguish service failure from compromise. Defenders use it in application gateways, microservices, and automation pipelines, often with backoff, queues, and fallback paths. Attackers may try to exploit weak resilience by triggering repeated failures or resource exhaustion, so circuit breakers help limit blast radius and preserve core operations.