Service Mesh Security: mTLS and Policy

Kubernetes does not encrypt pod-to-pod traffic by default. Every HTTP call, gRPC stream, and database connection between services travels as plaintext across the cluster network. If an attacker gains access to a node or taps into the CNI overlay, they see everything. Network policies control which pods can connect, but they cannot authenticate callers or encrypt what flows between them.

Service meshes close these gaps. By injecting a proxy alongside each workload, they add transparent mutual TLS encryption, cryptographic workload identity, and fine-grained authorization policies. Your application code never touches a certificate or checks an access control list. The mesh handles it at the infrastructure layer.