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RancherApplication · Suse

CVE-2018-20321

HIGH · 8.8 CVSS v3.0 Published 2019-04-10
Fix available
A fix is available. Upgrade to after 2.1.5 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An issue was discovered in Rancher 2 through 2.1.5. Any project member with access to the default namespace can mount the netes-default service account in a pod, and then use that pod to execute administrative privileged commands against the k8s cluster. This could be mitigated by isolating the default namespace in a separate project, where only cluster admins can be given permissions to access. As of 2018-12-20, this bug affected ALL clusters created or imported by Rancher.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

This is a privilege escalation vulnerability in Rancher 2 (versions through 2.1.5) where any project member with access to the default namespace can mount the netes-default service account in a pod. This allows the attacker to execute administrative privileged commands against the underlying Kubernetes cluster by leveraging the elevated permissions of the default service account.

MitigationIsolate the default namespace in a separate Rancher project where only cluster administrators have access permissions, preventing project members from mounting privileged service accounts.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
RancherApplication
Affected:>= 2.0.0, <= 2.1.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Rancher version
    Check the installed Rancher version in the UI under 'About Rancher' or via the API endpoint /meta/rancher/identity. Compare the version number against the affected range: >= 2.0.0 and <= 2.1.5
    Affected if Rancher version is 2.0.0 through 2.1.5 inclusive
  2. Verify project membership with default namespace access
    In Rancher UI, navigate to the target cluster and check which projects non-cluster-admin users belong to. For each project, inspect the namespace members under 'Resources' > 'Namespaces' to see if the default namespace is accessible to project members
    Affected if Any project member (non-cluster-admin) has been granted access to the default namespace in their project
  3. Confirm pod creation capability in default namespace
    As a project member, attempt to create a test pod or deploy a workload in the default namespace. Verify whether the user can submit pod specs through the Rancher UI or kubectl via the project's kubeconfig
    Affected if Project members can create pods in the default namespace
  4. Check service account mounting option
    When creating a pod/deployment in the default namespace via Rancher, inspect the pod spec form or YAML to see if the 'Service Account' field is editable or if the default service account can be specified in the pod spec
    Affected if Users can specify or retain the default service account when creating pods in the default namespace

The environment is affected if running Rancher 2.0.0-2.1.5 AND project members have access to create pods in the default namespace where they can leverage the netes-default service account for privilege escalation.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to a release after 2.1.5
Interim mitigation

Isolate the default namespace in a separate Rancher project where only cluster administrators have access permissions, preventing project members from mounting privileged service accounts.

Fix this in Rancher Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2018-20321 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data