Category: Envoy Upstream Failures

Problems where Envoy fails to communicate with an upstream service. This includes connection timeouts, connection refused errors, upstream overflow and cases where no healthy upstream hosts are available. It also covers request timeouts and unexpected stream resets from the upstream service.

ID	Title	Description	Category	Technology	Tags
CRE-2025-0118 High Impact: 7/10 Mitigation: 7/10	Envoy proxy unable to connect to upstream services	This rule detects when Envoy proxy is experiencing consistent failures connecting to upstream services, resulting in HTTP 503 (Service Unavailable) or 504 (Gateway Timeout) errors. These errors are typically accompanied by "UH" (upstream service unhealthy) or "UT" (upstream request timeout) response flags in Envoy access logs, indicating backend service connectivity issues that require immediate attention.	Envoy Upstream Failures	envoy	Envoy Proxy Load Balancer Envoy Upstream Errors Envoy Service Unavailable Envoy Gateway Timeout