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TraefikApplication

CVE-2026-35051

CRITICAL · 10.0 CVSS v3.1 Published 2026-04-30
Fix available
A fix is available. Upgrade to 2.11.43 / 3.6.14 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click Patch available

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
Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is an authentication bypass vulnerability in Traefik's ForwardAuth middleware when trustForwardHeader=false is configured and Traefik is deployed behind a trusted upstream proxy. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.

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

Authentication bypass in Traefik's ForwardAuth middleware when trustForwardHeader=false is configured with a trusted upstream proxy, allowing unauthenticated attackers to bypass authentication controls.

MitigationUpgrade to Traefik versions 2.11.43, 3.6.14, or 3.7.0-rc.2, or review and adjust ForwardAuth trustForwardHeader configuration to align with deployment topology.

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
TraefikApplication
Affected:< 2.11.43>= 3.0.0, < 3.6.14= 3.7.0

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/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. Check Traefik version
    Run 'traefik version' or inspect the container/binary version to determine the installed version
    Affected if Installed version is < 2.11.43, >= 3.0.0 and < 3.6.14, or exactly 3.7.0
  2. Identify ForwardAuth middleware usage
    Review Traefik configuration files (static and dynamic) for ForwardAuth middleware definitions, or run 'traefik hub' or API query to list middleware
    Affected if ForwardAuth middleware is configured and in use
  3. Verify trustForwardHeader setting
    Inspect the ForwardAuth middleware configuration for 'trustForwardHeader: false' or the equivalent configuration in your provider (Docker labels, Kubernetes annotations, file, etc.)
    Affected if trustForwardHeader is explicitly set to false
  4. Check for trusted proxy configuration
    Inspect Traefik configuration for trustedIPs, trustedIP, or similar settings in the entrypoint or forwarding configuration that designate trusted upstream proxies
    Affected if Trusted proxy IPs are configured (trustedIPs is set), allowing forwarded headers from that proxy to be trusted

User is affected if running an affected Traefik version, ForwardAuth middleware is active, trustForwardHeader is set to false, AND a trusted proxy is configured, allowing header manipulation for authentication bypass.

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 2.11.43 / 3.6.14 or later
Fixed in 2.11.433.6.14
Vendor patch github.com →
Interim mitigation

Upgrade to Traefik versions 2.11.43, 3.6.14, or 3.7.0-rc.2, or review and adjust ForwardAuth trustForwardHeader configuration to align with deployment topology.

Recommended fix High confidence

2.11.43 (for v2.x) or 3.6.14 (for v3.x)

  1. 1. Identify your current Traefik version using `traefik --version`
  2. 2. Determine whether you are on Traefik v2 or v3 from the version output
  3. 3. For Traefik v2.x users: Upgrade to version 2.11.43 or later
  4. 4. For Traefik v3.x users (excluding 3.7.0-rc.2): Upgrade to version 3.6.14
  5. 5. Review your ForwardAuth middleware configuration and verify trustForwardHeader settings align with your deployment topology
  6. 6. Test the upgraded configuration in a non-production environment before deploying
  7. 7. Apply the update to production and verify authentication behavior
Caveat Review Traefik v2.11 and v3.6 release notes for any breaking changes specific to your configuration

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

Fix this in Traefik Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,770
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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-2026-35051 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