dbcve.org
Nginx Gateway FabricWeb server / proxy · F5

CVE-2026-11311

MEDIUM · 6.5 CVSS v3.1 Published 2026-06-17
Fix available
A fix is available. Upgrade to 2.6.4 or later.
See remediation →
71/100
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
When NGINX Plus is configured as the data plane for NGINX Gateway Fabric, an injection vulnerability exists in the NGINX configuration generator component of NGINX Gateway Fabric. User-supplied string values from the NginxProxy Custom Resource Definition serverTokens field and the AuthenticationFilter Custom Resource Definition extraAuthArgs field are rendered directly into NGINX configuration templates without sanitization or escaping. An authenticated attacker with permission to create or modify these Custom Resource Definitions may craft values that inject arbitrary NGINX configuration directives. This is a control plane issue; there is no data plane exposure from the vulnerability trigger itself. 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 · high confidence

This is a configuration injection vulnerability in NGINX Gateway Fabric's NGINX configuration generator. Authenticated attackers with permissions to create or modify NginxProxy or AuthenticationFilter CRDs can supply specially crafted values in the serverTokens and extraAuthArgs fields that get rendered directly into NGINX config templates without sanitization, enabling injection of arbitrary NGINX directives.

MitigationImplement strict input validation and escaping for the serverTokens and extraAuthArgs fields in the CRD controllers before rendering into templates, using allowlist validation where possible.

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 Gateway FabricWeb server / proxy
Affected:>= 2.5.0, < 2.6.4

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
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/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 F5 Nginx Gateway Fabric installation and version
    Run 'kubectl get pods -n <namespace> -o jsonpath="{.items[0].spec.containers[0].image}"' to retrieve the nginx-gateway-fabric container image, then extract the version from the image tag
    Affected if The installed version is >= 2.5.0 and < 2.6.4
  2. Check for NginxProxy CRDs in the cluster
    Run 'kubectl get nginxproxies -A' to list all NginxProxy resources, then 'kubectl get nginxproxy <name> -n <namespace> -o yaml' to inspect each one for serverTokens or extraAuthArgs fields
    Affected if Any NginxProxy resource contains configured serverTokens or extraAuthArgs fields with user-supplied values
  3. Check for AuthenticationFilter CRDs in the cluster
    Run 'kubectl get authenticationfilters -A' to list all AuthenticationFilter resources, then inspect each for extraAuthArgs field configuration
    Affected if Any AuthenticationFilter resource contains configured extraAuthArgs fields with user-supplied values
  4. Inspect generated NGINX configuration
    Access the nginx.conf generated by the gateway fabric (typically via configdump or by exec into the nginx-gateway-fabric pod and cat the config file) and search for directive patterns that appear injected or unexpected in sections related to server_tokens or auth_request_set
    Affected if The generated NGINX config contains directives in server_tokens or auth_request_set sections that were not intentionally configured or contain shell-like characters

You are affected if F5 Nginx Gateway Fabric version is between 2.5.0 and 2.6.4 (exclusive) AND you have NginxProxy or AuthenticationFilter CRDs with serverTokens or extraAuthArgs fields configured using untrusted input.

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 2.6.4 or later
Fixed in 2.6.4
Interim mitigation

Implement strict input validation and escaping for the serverTokens and extraAuthArgs fields in the CRD controllers before rendering into templates, using allowlist validation where possible.

Recommended fix High confidence

Nginx Gateway Fabric >= 2.6.4

  1. 1. Identify the current Nginx Gateway Fabric version deployed in your cluster using 'kubectl get pods -n <namespace>' or your Helm release
  2. 2. Review the NginxProxy and AuthenticationFilter Custom Resource Definitions in your cluster for any user-supplied values in the serverTokens and extraAuthArgs fields respectively
  3. 3. Plan an upgrade to Nginx Gateway Fabric version 2.6.4 or later
  4. 4. Before upgrading, backup your existing CRD configurations
  5. 5. Execute the upgrade using your existing deployment method (Helm upgrade or kubectl apply)
  6. 6. After upgrade, verify that Nginx Gateway Fabric pods are running correctly
  7. 7. Validate that existing NginxProxy and AuthenticationFilter resources are functioning as expected
Caveat Review release notes for 2.6.4 for any configuration or behavioral changes that may affect existing deployments

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

Fix this in Nginx Gateway Fabric Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,600
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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-2026-11311 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
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