# 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.

- **Severity:** Medium 5.7 (`CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **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:** Yes
- **Published:** 14 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** GHSA-5587-2x54-jj6h, GO-2026-6018

## 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 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-54246?

3 open source packages ship an affected version, including github.com/zalando/skipper.


| Package | Ecosystem | 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.

## Is CVE-2026-54246 being exploited?

There is no known exploitation of CVE-2026-54246 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54246 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-54246 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/zalando/skipper (Go): affected all versions; fixed in 0.27.13
- github.com/zalando/skipper (Go): affected all versions; fixed in 0.27.13
- github.com/zalando/skipper (Go): affected all versions; fixed in 0.27.13

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-54246/ (Markdown: https://insights.sbomify.com/CVE-2026-54246/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54246
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54246
- OSV: https://osv.dev/vulnerability/CVE-2026-54246

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54246/
Summaries are generated and may contain mistakes; the official description above is the record.