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Medium, CVSS 6.9amended

Traefik's errors middleware forwards Authorization and Cookie headers to separate error page service

CVE-2026-41181GHSA-p6hg-qh38-555r

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
    <= 3.6.14>= 3.7.0-rc.0, <= 3.7.0-rc.2
    Fixed in
    3.6.15, 3.7.0-rc.3

  • Go github.com/traefik/traefik/v2

    Affected
    <= 2.11.43
    Fixed in
    2.11.44

  • Go github.com/traefik/traefik

    Affected
    every version
    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:L/SI:N/SA:N · score source
EPSS
  • CVE-2026-41181: 0.45% estimated exploitation activity in the next 30 days; percentile 38.80 (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 information disclosure vulnerability in Traefik's errors (custom error pages) middleware. When the backend returns a response matching the configured status range, the middleware forwards the original request's complete header set, including Authorization, Cookie, and other authentication material, to the separate error page service rather than only the minimal context needed to render the error page. This behavior is undocumented: the documentation states only that Host is forwarded by default, so operators are not warned that sensitive credentials are shared across service boundaries. Deployments using the errors middleware with a distinct error page service may inadvertently expose end-user credentials to infrastructure that was not intended to receive them. Patches - https://github.com/traefik/traefik/releases/tag/v2.11.44 - https://github.com/traefik/traefik/releases/tag/v3.6.15 - https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.3 For…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-p6hg-qh38-555r

  2. Revision 2 · amended ·

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

  3. Revision 1 · created ·

    Published from osv record GO-2026-5532

Agent brief

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# Patch Next advisory brief: CVE-2026-41181

Advisory: Traefik's errors middleware forwards Authorization and Cookie headers to separate error page service
IDs: CVE-2026-41181, GHSA-p6hg-qh38-555r
Record: https://patchnext.com/advisories/cve-2026-41181 (revision 3, source checked 26 Oct 2026, 15:22 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 3.7.0-rc.3, 3.6.15; github.com/traefik/traefik/v2 2.11.44. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/traefik/traefik/v3: affected <= 3.6.14; >= 3.7.0-rc.0, <= 3.7.0-rc.2; fixed in 3.6.15, 3.7.0-rc.3
- Go github.com/traefik/traefik/v2: affected <= 2.11.43; fixed in 2.11.44
- Go github.com/traefik/traefik: affected every version

## 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/GO-2026-5532 (OSV record GO-2026-5532 lists affected ranges: Go github.com/traefik/traefik >=0; Go github.com/traefik/traefik/v2 >=0 =0 =3.7.0-rc.1 <3.7.0-rc.3 (fixed))
- Verified: https://github.com/advisories/GHSA-p6hg-qh38-555r (GitHub-reviewed advisory GHSA-p6hg-qh38-555r lists affected ranges: Go github.com/traefik/traefik/v2 >=0 =0 =3.7.0-rc.0 <=3.7.0-rc.2)

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