CVE-2026-54246 Skipper routesrv-no-auth: All routesrv API Endpoints Lack Authentication
Attackers can access sensitive cluster configuration data via unauthenticated API endpoints in Skipper routesrv, exposing backend URLs and shard addresses.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54246?
CVE-2026-54246 is a medium-severity missing authorization vulnerability in zalando skipper, published on 14 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Skipper is an HTTP router and reverse proxy for service composition. Prior to 0.27.13, the routesrv component serves cluster-wide control-plane data without application-layer authentication through /routes, /routes/{zone}, /swarm/redis/shards, and /swarm/valkey/shards. The handlers registered in routesrv/routesrv.go, eskipBytes.ServeHTTP in routesrv/eskipbytes.go, RedisHandler.ServeHTTP in routesrv/redishandler.go, and ValkeyHandler.ServeHTTP in routesrv/valkeyhandler.go only restrict HTTP methods and do not authenticate callers. A compromised or otherwise attacker-controlled pod that can reach routesrv on the Kubernetes cluster network can bypass its namespace-scoped RBAC and read Ingress and RouteGroup backend URLs, filter-chain and OAuth or OIDC path details, and Redis or Valkey shard addresses across namespaces. NetworkPolicy can restrict reachability but does not remove the missing-authentication condition, and the established impact is confidentiality exposure rather than direct integrity or availability loss. This issue is fixed in version 0.27.13.
Weakness: CWE-306
Which versions are affected by CVE-2026-54246?
3 open source packages ship an affected version, including github.com/zalando/skipper.
| Package | Affected | Fixed in |
|---|---|---|
github.com/zalando/skipper Go | All versions | 0.27.13 |
github.com/zalando/skipper Go | All versions | 0.27.13 |
github.com/zalando/skipper Go | All versions | 0.27.13 |
How do I fix CVE-2026-54246?
Upgrade github.com/zalando/skipper to 0.27.13 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-54246 being exploited?
There is no known exploitation of CVE-2026-54246 in the wild and no public exploit code.
Sources
Also known as GHSA-5587-2x54-jj6h, GO-2026-6018.