CVE-2021-25318
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 · uneditedA Incorrect Permission Assignment for Critical Resource vulnerability in Rancher allows users in the cluster to modify resources they should not have access to. This issue affects: Rancher versions prior to 2.5.9 ; Rancher versions prior to 2.4.16.
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 confidenceRancher versions prior to 2.5.9 and 2.4.16 contain an incorrect permission assignment vulnerability where cluster users can modify resources they should not have access to. This is an authorization bypass allowing privilege escalation within the cluster.
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< 2.4.16>= 2.5.0, < 2.5.9CVSS 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:3.1/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 checksWork through these to decide whether this CVE applies to you.
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Determine Rancher server versionAccess the Rancher UI and navigate to the support page, or query the Rancher API endpoint /v1 management.cattle.io.setting/fleet-private-registry. Alternatively, check the Helm chart or Docker container version if deployed via those methods.Affected if The installed version is less than 2.4.16, or greater than or equal to 2.5.0 but less than 2.5.9
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Identify cluster users with elevated accessReview the cluster's RBAC role bindings and user assignments through the Rancher UI under Clusters > Security > Members, or via kubectl get clusterrolebindings if kubectl is configured.Affected if Non-admin users are assigned elevated roles within the cluster who should have restricted access to critical resources
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Verify authorization configuration for cluster-scoped resourcesTest whether cluster users without full administrator privileges can modify resources outside their intended scope by attempting to create, modify, or delete resources in namespaces or projects they should not have access to.Affected if Users can perform operations on resources that their assigned role should explicitly deny
You are affected if your Rancher version is below 2.4.16 or between 2.5.0 and 2.5.8 inclusive, and you have cluster users who could potentially exploit the authorization bypass to access resources beyond their permitted scope.
Generated from the published advisory. Verify against your own configuration.
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.
dbcve · scoped2.4.162.5.9
Upgrade Rancher to version 2.5.9 or 2.4.16 or later to remediate the improper permission assignment for critical resources.
Rancher 2.4.16 or Rancher 2.5.9 (depending on your major version branch)
- Backup your Rancher environment and Kubernetes clusters before upgrading
- Upgrade Rancher to version 2.4.16 if currently on the 2.4.x line
- Upgrade Rancher to version 2.5.9 if currently on the 2.5.x line
- After upgrading, verify that the permission assignments are correctly enforced
- Review user roles and permissions to ensure they align with expected access controls
- Test that users can only modify resources they are authorized to access
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-25318 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-25318 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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