GHSA-5587-2x54-jj6h Skipper's routesrv-no-auth component: All routesrv API Endpoints Lack Authentication
DescriptionThe `routesrv` component exposes the full cluster route topology (Ingress/RouteGroup configurations, backend URLs, filter chains, OAuth/OIDC callback paths) and cache-cluster topology (Redis/Valkey shard addresses) over plain HTTP with **zero authentication**. Any pod in the Kubernetes cluster can reach routesrv via its predictable DNS name and retrieve sensitive cluster-wide routing and cache infrastructure data.Vulnerable Code**routesrv/routesrv.go:87-99,114-137** — all handler registrations on the main mux:**routesrv/eskipbytes.go:134-196** — `eskipBytes.ServeHTTP`:**routesrv/redishandler.go:28-41** — `RedisHandler.ServeHTTP`:**routesrv/valkeyhandler.go:28-41** — `ValkeyHandler.ServeHTTP`:Attack Path**Initial Compromise**: Attacker compromises any pod in the Kubernetes cluster (via application CVE, supply-chain attack, malicious container image, etc.)**Discovery**: Attacker discovers routesrv via predictable Kubernetes DNS name: `skipper-ingress-routesrv.kube-system.svc.cluster.local:9090` (documented at `docs/tutorials/operations.md:108`, `docs/tutorials/ratelimit.md:137,197`)**Data Extraction without Auth**:`GET http://<routesrv>:9090/routes` → All Ingress/RouteGroup configurations across ALL namespaces`GET http://<routesrv>:9090/swarm/redis/shards` → Redis cache cluster node addresses`GET http://<routesrv>:9090/swarm/valkey/shards` → Valkey cache cluster node addresses**Subsequent Attacks**: With cache cluster topology, attacker can perform direct cache-level attacks (ratelimit data manipulation, session data exfiltration)Permission Boundary AnalysisThe routesrv uses a ServiceAccount with **cluster-wide RBAC** to list Ingress (networking.k8s.io), RouteGroup (zalando.org), Endpoints, and Services across all namespaces (see `clusterclient.go:648-653` `fetchClusterState`). The kube-apiserver requires proper ServiceAccount token + RBAC authorization for the Kubernetes API itself, but **routesrv exposes the aggregated data over HTTP with zero authentication**.A compromised pod with limited RBAC (restricted to its own namespace) can bypass Kubernetes RBAC entirely by reading routesrv. This crosses the boundary from *"namespace-scoped Kubernetes workload with restricted RBAC"* to *"full cluster route topology across all namespaces"*.No NetworkPolicy manifests exist in the `deploy/` directory. The default Kubernetes flat network model allows any pod to reach any service, further widening the attack surface.Exposed Data| Endpoint | Data Exposed | Impact |
|----------|-------------|--------|
| `GET /routes` | All ingress/routegroup backends: internal service URLs, filter chains (auth, rate limiting, OAuth, JWT, OPA policies), load balancer group membership | Cluster-wide reconnaissance, targeted backend attacks |
| `GET /routes/{zone}` | Zone-scoped subset of above route data | Same, scoped |
| `GET /swarm/redis/shards` | Redis cluster internal IP:port pairs | Direct cache-level attacks, ratelimit data manipulation |
| `GET /swarm/valkey/shards` | Valkey cluster internal IP:port pairs | Same |Additionally, the data-plane client (`eskipfile/remote.go:190-219`) also performs plain HTTP GET with no credentials — only an ETag header is sent — confirming that no auth capability exists in the architecture at all.MitigationAdd authentication to all routesrv HTTP endpoints (basic auth, bearer token, mTLS, or shared secret) via flag `-route-server-filters=""`Deploy Kubernetes NetworkPolicies restricting ingress to routesrv to only the data-plane skipper pod selectorsConsider using mutual TLS authentication between data-plane and control-plane componentsNetworkPolicy does not remove the missing-auth conditionRestrictive NetworkPolicies are a valid mitigation, but they are not an application-layer authentication mechanism. The security-relevant defect remains that routesrv serves control-plane-derived data to unauthenticated callers whenever network reachability exists.Impact framingThis report does **not** rely on claiming direct integrity or availability impact. The verified issue is a confidentiality-focused control-plane exposure: route definitions, backend topology, filter-chain details, and Redis/Valkey shard addresses become readable to any reachable in-cluster client.Resources`routesrv/routesrv.go:87-99` — handler registration (zero auth)`routesrv/eskipbytes.go:134-196` — route data handler (no auth)`routesrv/redishandler.go:28-41` — Redis shard handler (no auth)`routesrv/valkeyhandler.go:28-41` — Valkey shard handler (no auth)`dataclients/kubernetes/clusterclient.go:648-653` — `fetchClusterState()` — shows cluster-wide RBAC`eskipfile/remote.go:190-219` — data-plane client also has no auth capability`docs/tutorials/operations.md:108`, `docs/tutorials/ratelimit.md:137,197` — documented routesrv DNS name
CVSS v3.1 score: 5.7