Skipper's routesrv-no-auth component: All routesrv API Endpoints Lack Authentication (CVE-2026-54246)
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.
CVSS v3.1
Score 5.7medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The routesrv component of Skipper, an HTTP router and reverse proxy, exposes several API endpoints (/routes, /routes/{zone}, /swarm/redis/shards, /swarm/valkey/shards) without application-layer authentication in versions prior to 0.27.13. The handlers only restrict HTTP methods but do not authenticate callers, enabling an attacker with access to the Kubernetes cluster network to bypass namespace-scoped RBAC controls and read sensitive configuration data across namespaces. NetworkPolicy can limit network reachability but does not address the lack of authentication. The vulnerability is identified as CWE-306 (Missing Authentication for Critical Function) and has a CVSS 3.1 score of 5.7 (medium severity).
Potential Impact
An attacker who controls or compromises a pod with network access to routesrv can read cluster-wide control-plane data such as Ingress and RouteGroup backend URLs, filter-chain and OAuth/OIDC path details, and Redis or Valkey shard addresses across namespaces. This leads to a confidentiality breach but does not affect data integrity or availability.
Mitigation Recommendations
Upgrade Skipper to version 0.27.13 or later, where this authentication issue is fixed. NetworkPolicy can reduce exposure by restricting network access to routesrv, but it does not eliminate the underlying authentication vulnerability.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-5587-2x54-jj6h
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-54246"]
- Ecosystems
- ["Go"]
- Database Specific Severity
- MODERATE
- Cvss Version
- 3.1
Threat ID: 6a5b60962d1edb114c84a5ea
Added to database: 07/18/2026, 11:16:38 UTC
Last enriched: 09/21/2026, 22:17:55 UTC
Last updated: 10/17/2026, 06:48:18 UTC
Views: 226
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