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Nginx Ingress ControllerWeb server / proxy · F5

CVE-2026-52865

MEDIUM · 6.5 CVSS v3.1 Published 2026-07-15
Fix available
A fix is available. Upgrade to 5.5.2 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click 5 weeks old

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
When NGINX Ingress Controller processes Ingress or TransportServer resources, an authenticated, remote attacker with permission to create or modify Ingress or TransportServer resources can cause the NGINX Ingress Controller process to terminate. Impact: The NGINX Ingress Controller control plane process terminates and enters a persistent crash loop while the malformed Ingress or TransportServer resource remains in the cluster. This vulnerability allows a remote, authenticated attacker with at least Ingress or TransportServer resource write access to cause a denial-of-service (DoS) on the NGINX Ingress Controller system. There is no data plane exposure; this is a control plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

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 · moderate confidence

The NGINX Ingress Controller lacks proper input validation when processing Ingress or TransportServer resources, allowing a malformed resource to trigger a panic/crash in the controller process. The controller enters a persistent crash loop because the offending resource remains in the cluster and is repeatedly reprocessed on restart.

MitigationImplement admission control (e.g., ValidatingWebhookConfiguration) to validate Ingress/TransportServer resources before they are applied, and restrict RBAC permissions to limit who can create/modify these resources to trusted users only.

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
Nginx Ingress ControllerWeb server / proxy
Affected:>= 3.5.0, <= 3.7.2>= 4.0.0, <= 4.0.1>= 5.0.0, < 5.5.2

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/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 installed F5 Nginx Ingress Controller version
    Run 'kubectl get deployment -n <ingress-namespace> -o jsonpath="{.items[*].spec.template.spec.containers[?(@.name=="controller")].image}"' or inspect the controller pod image directly with 'kubectl get pod -n <ingress-namespace> -o jsonpath="{.items[*].spec.containers[*].image}"'
    Affected if The version falls within 3.5.0-3.7.2, 4.0.0-4.0.1, or 5.0.0-5.5.1 (less than 5.5.2)
  2. Check for Ingress resources in the cluster
    Run 'kubectl get ingress --all-namespaces' to list all Ingress resources
    Affected if Any Ingress resources exist in the cluster and the controller version is affected
  3. Check for TransportServer resources
    Run 'kubectl get transportserver --all-namespaces' (or check the custom resource definition for TransportServer) to see if TransportServer resources are defined
    Affected if Any TransportServer resources exist and the controller version is affected
  4. Inspect controller pod status for crash loop
    Run 'kubectl get pods -n <ingress-namespace> -o wide' and check the STATUS column; also run 'kubectl describe pod <controller-pod> -n <ingress-namespace>' and look at Events for repeated crash/restart entries
    Affected if The controller pod shows RestartCount increasing or status showing CrashLoopBackOff with events indicating the controller is crashing repeatedly

You are affected if your F5 Nginx Ingress Controller version is 3.5.0-3.7.2, 4.0.0-4.0.1, or 5.0.0-5.5.1 AND you have Ingress or TransportServer resources in the cluster that could be malformed, or you observe the controller in a persistent crash loop.

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.

dbcve · scoped
Upgrade available Upgrade to 5.5.2 or later
Fixed in 5.5.2
Interim mitigation

Implement admission control (e.g., ValidatingWebhookConfiguration) to validate Ingress/TransportServer resources before they are applied, and restrict RBAC permissions to limit who can create/modify these resources to trusted users only.

Recommended fix High confidence

5.5.2 or later (for 5.x branch); for 3.x and 4.x branches, upgrade to 5.x 5.5.2+

  1. 1. Identify the current NGINX Ingress Controller version running in your cluster using: kubectl get pods -n <ingress-namespace> -o jsonpath='{.items[0].spec.containers[0].image}'
  2. 2. Check the Helm release if using Helm: helm list -n <ingress-namespace> and review the chart version
  3. 3. Plan the upgrade considering your current branch (3.x, 4.x, or 5.x) and ensure compatibility with your Kubernetes version
  4. 4. For Helm-based installations, update the Helm chart to version 5.5.2 or later: helm upgrade <release-name> nginx-stable/nginx-ingress -n <ingress-namespace>
  5. 5. For manual YAML installations, apply the new version manifest: kubectl apply -f https://raw.githubusercontent.com/nginxinc/kubernetes-ingress/v5.5.2/deployments/helm-chart/nginx-ingress-5.5.2.tgz
  6. 6. Verify the new version is running: kubectl get pods -n <ingress-namespace> -o jsonpath='{.items[0].spec.containers[0].image}'
  7. 7. Monitor the NGINX Ingress Controller pods for stability and ensure no crash loops occur
Caveat Review F5 migration guides when moving from 3.x/4.x to 5.x as there may be configuration and API changes; test thoroughly in a non-production environment before deploying to production

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Nginx Ingress Controller 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-2026-52865 in production — separate from our analysis above.

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