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Medium, CVSS 6.9amended

Traefik: ForwardAuth middleware leaks X-Forwarded-Port spoofing via untrusted X-Forwarded-Proto when trustForwardHeader=false

CVE-2026-54764GHSA-3q9r-p662-5j8m

What to do

Partial vendor fix. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Go github.com/traefik/traefik/v3

    Affected
    <= 3.6.21>= 3.7.0, <= 3.7.5
    Fixed in
    3.6.22, 3.7.6

  • Go github.com/traefik/traefik/v2

    Affected
    <= 2.11.50
    Fixed in
    2.11.51

  • Go github.com/traefik/traefik

    Affected
    <= 1.7.34
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N · score source
EPSS
  • CVE-2026-54764: 0.28% estimated exploitation activity in the next 30 days; percentile 20.64 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary There is a medium severity vulnerability in Traefik's ForwardAuth middleware. Even when configured with trustForwardHeader: false, Traefik derives the X-Forwarded-Port header sent to the authentication service from the original incoming request instead of the sanitized forwarded request. As a result, an unauthenticated remote attacker can inject an X-Forwarded-Proto: https header over a plain HTTP connection and cause Traefik to forward X-Forwarded-Port: 443 to the auth service, bypassing port-based authorization checks. This is a regression of the incomplete fix for GHSA-6384-m2mw-rf54, which addressed the X-Forwarded-Proto and X-Forwarded-Prefix spoofing vectors but missed the X-Forwarded-Port vector. Patches - https://github.com/traefik/traefik/releases/tag/v2.11.51 - https://github.com/traefik/traefik/releases/tag/v3.6.22 - https://github.com/traefik/traefik/releases/tag/v3.7.6 For more information If you have any questions or comments about this advisory, please open an…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-3q9r-p662-5j8m

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GO-2026-6202

  4. Revision 1 · created ·

    Published from osv record GHSA-3q9r-p662-5j8m

Agent brief

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# Patch Next advisory brief: CVE-2026-54764

Advisory: Traefik: ForwardAuth middleware leaks X-Forwarded-Port spoofing via untrusted X-Forwarded-Proto when trustForwardHeader=false
IDs: CVE-2026-54764, GHSA-3q9r-p662-5j8m
Record: https://patchnext.com/advisories/cve-2026-54764 (revision 4, source checked 26 Oct 2026, 15:28 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/traefik/traefik/v3 3.7.6, 3.6.22; github.com/traefik/traefik/v2 2.11.51. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/traefik/traefik/v3: affected <= 3.6.21; >= 3.7.0, <= 3.7.5; fixed in 3.6.22, 3.7.6
- Go github.com/traefik/traefik/v2: affected <= 2.11.50; fixed in 2.11.51
- Go github.com/traefik/traefik: affected <= 1.7.34

## Suggested inspection (read-only)
- Go github.com/traefik/traefik/v3: check the installed version with your package manager.
- Go github.com/traefik/traefik/v2: check the installed version with your package manager.
- Go github.com/traefik/traefik: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/traefik/traefik/v3, github.com/traefik/traefik/v2, github.com/traefik/traefik.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-3q9r-p662-5j8m (OSV record GHSA-3q9r-p662-5j8m lists affected ranges: Go github.com/traefik/traefik/v2 >=0 =0 =3.7.0 =0 <=1.7.34)
- Verified: https://osv.dev/vulnerability/GO-2026-6202 (OSV record GO-2026-6202 lists affected ranges: Go github.com/traefik/traefik >=0; Go github.com/traefik/traefik/v2 >=0 =0 =3.7.0 <3.7.6 (fixed))
- Verified: https://github.com/advisories/GHSA-3q9r-p662-5j8m (GitHub-reviewed advisory GHSA-3q9r-p662-5j8m lists affected ranges: Go github.com/traefik/traefik/v2 >=0 =0 =3.7.0 =0 <=1.7.34)

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