# CVE-2026-55998: Cluster Existence Oracle via Unauthenticated Import Endpoint

> Attackers can enumerate valid cluster IDs by observing HTTP response differences from an unauthenticated import endpoint, exposing infrastructure topology.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Aug 2026
- **Updated:** 5 Aug 2026
- **Also known as:** GHSA-23h9-rr79-r3gh

## What is CVE-2026-55998?

CVE-2026-55998 is a medium-severity vulnerability in SUSE Rancher, published on 5 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The endpoint /v3/import/{token}_{clusterId}.yaml retrieves the cluster object before validating the token. When a valid cluster ID references a cluster that has private registry secrets configured, a nil pointer dereference in pkg/systemtemplate/private_registry.go causes the request to return HTTP 502 Bad Gateway. For cluster IDs that do not exist, the endpoint returns HTTP 200. This observable difference in response codes constitutes a reliable enumeration oracle.

Weakness: CWE-204 (Observable Response Discrepancy)

## Which versions are affected by CVE-2026-55998?


## How do I fix CVE-2026-55998?

No fix has been published for CVE-2026-55998 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-55998 being exploited?

There is no known exploitation of CVE-2026-55998 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55998 and fix it if it is affected.

What it is: CVE-2026-55998 is a medium-severity vulnerability in SUSE Rancher, published on 5 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-55998 in the wild and no public exploit code.

Affected product: SUSE Rancher. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-55998/ (Markdown: https://insights.sbomify.com/CVE-2026-55998/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55998
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55998
- OSV: https://osv.dev/vulnerability/CVE-2026-55998

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55998/
Summaries are generated and may contain mistakes; the official description above is the record.