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Vulnerability · Published Sep 14, 2026 · Assigned by GitHub_M

CVE-2026-54246Skipper routesrv-no-auth: All routesrv API Endpoints Lack Authentication

Medium 5.7

In plain English

A medium-severity missing authentication in skipper from zalando. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.7Medium
Exploit odds (30 days)0.3%top 72.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Gogithub.com/zalando/skipper0.27.13GHSA-5587-2x54-jj6h
Gogithub.com/zalando/skipper0.27.13GO-2026-6018

Affected products (as reported)

VendorProductVersions
zalando skipper < 0.27.13

Weakness: CWE-306 · Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

References