Token Validation Flaw in Rancher Affects Private Registry Secrets
CVE-2026-55998

5.3MEDIUM

Key Information:

Vendor

Suse
Status
Rancher
Vendor
CVE Published:
5 August 2026

What is CVE-2026-55998?

A vulnerability in Rancher's token validation mechanism allows an attacker to exploit the /v3/import/{token}_{clusterId}.yaml endpoint. This endpoint retrieves the cluster object without validating the provided token. If a valid cluster ID is used and the referenced cluster has private registry secrets configured, a nil pointer dereference occurs, causing the system to respond with an HTTP 502 Bad Gateway error. Conversely, requests to non-existent cluster IDs yield an HTTP 200 response, creating a clear discrepancy in the response codes that can be exploited for enumerating valid cluster configurations.

Affected Version(s)

Rancher 2.14.0 < 2.14.4

Rancher 2.13.0 < 2.13.8

Rancher 2.12.0 < 2.12.12

References

https://github.com/rancher/rancher/security/advisories/GH...
https://bugzilla.suse.com/show_bug.cgi?id=CVE-2026-55998

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

This vulnerability was discovered and reported by Michael Wollner (@ibonok) from Deutsche Telekom AG.
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