CVE-2026-55998

Cluster Existence Oracle via Unauthenticated Import Endpoint

MEDIUM
5.3
CVSS Score
Published: August 5, 2026 at 07:51 AM UTC
Updated: October 24, 2026 at 04:10 PM UTC
1 product affected across 1 vendorRancher

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

2.11.0 ≤ v < 2.11.162.12.0 ≤ v < 2.12.122.13.0 ≤ v < 2.13.82.14.0 ≤ v < 2.14.42.11.02.12.02.13.02.14.0
Affected range stops below 2.11.16, so it looks safe — our inference, not a vendor statement
Affected range stops below 2.12.12, so it looks safe — our inference, not a vendor statement
Affected range stops below 2.13.8, so it looks safe — our inference, not a vendor statement
Affected range stops below 2.14.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMsuse
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-204

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