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KubernetesApplication

CVE-2020-8555

MEDIUM · 6.3 CVSS v3.1 Published 2020-06-05
Fix available
A fix is available. Upgrade to 1.15.11 / 1.16.9 or later.
See remediation →
69/100
Remediation priority · Elevated
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
The Kubernetes kube-controller-manager in versions v1.0-1.14, versions prior to v1.15.12, v1.16.9, v1.17.5, and version v1.18.0 are vulnerable to a Server Side Request Forgery (SSRF) that allows certain authorized users to leak up to 500 bytes of arbitrary information from unprotected endpoints within the master's host network (such as link-local or loopback services).

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

kube-controller-manager contains an SSRF vulnerability where certain authorized users can cause the controller to make requests to arbitrary URLs, including link-local or loopback services on the master node, leaking up to 500 bytes of information. The attack requires authentication but does not require elevated privileges beyond standard user access.

MitigationUpgrade Kubernetes to v1.15.12+, v1.16.9+, v1.17.5+, or v1.18.1+ to patch the kube-controller-manager SSRF vulnerability. If immediate upgrade is not possible, restrict access to the kube-controller-manager API and monitor for suspicious requests to internal endpoints.

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
KubernetesApplication
Affected:< 1.15.11>= 1.16.0, < 1.16.9>= 1.17.0, < 1.17.5= 1.18.0
FedoraOperating system
Affected:= 32

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
High
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

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 kube-controller-manager version
    Run 'kube-controller-manager --version' on the master node, or check the container image tag if running as a pod via 'kubectl get pods -n kube-system -o jsonpath="{.items[?(@.spec.containers[0].name==\"kube-controller-manager\")].spec.containers[0].image}"', or check the package version with 'rpm -q kube-controller-manager' on Fedora/RHEL systems
    Affected if The version is < 1.15.11, 1.16.0-1.16.9, 1.17.0-1.17.5, or exactly 1.18.0 (or the package is from Fedora 32)
  2. Verify kube-controller-manager API accessibility
    Check if the kube-controller-manager service or endpoint is exposed externally or accessible to non-privileged network segments. Review the --bind-address flag in the controller manager manifest (typically /etc/kubernetes/manifests/kube-controller-manager.yaml) and any firewall or network policies
    Affected if The kube-controller-manager API port (default 10252 or 10257 with TLS) is accessible from user-accessible networks rather than restricted to master node only
  3. Review RBAC permissions for controller-manager endpoints
    Run 'kubectl auth can-i get / --subresource=endpoint --as=<test-user>' for a standard non-admin user, or review ClusterRoleBindings with 'kubectl get clusterrolebindings -o wide' to see which users or groups have get/list permissions on controller manager resources
    Affected if Standard authenticated users (without elevated privileges) have permission to query controller-manager endpoints, allowing them to trigger the SSRF
  4. Check for suspicious internal requests in audit logs
    Review Kubernetes audit logs for requests to kube-controller-manager endpoints with unusual destination URLs, or monitor API server logs for requests with Link-Local or loopback destinations (127.0.0.0/8, 169.254.0.0/16)
    Affected if Audit logs show requests from kube-controller-manager to internal loopback or link-local addresses that were not initiated by system components

You are affected if your kube-controller-manager version falls within the vulnerable range AND standard authenticated users can access the controller-manager API endpoints to trigger the SSRF.

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 1.15.11 / 1.16.9 / 1.17.5 or later
Fixed in 1.15.111.16.91.17.5
Interim mitigation

Upgrade Kubernetes to v1.15.12+, v1.16.9+, v1.17.5+, or v1.18.1+ to patch the kube-controller-manager SSRF vulnerability. If immediate upgrade is not possible, restrict access to the kube-controller-manager API and monitor for suspicious requests to internal endpoints.

Fix this in Kubernetes Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2020-8555 in production — separate from our analysis above.

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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