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Medium, CVSS 6.3

Traefik Affected by BasicAuth Middleware Timing Attack Allows Username Enumeration

CVE-2026-32595GHSA-g3hg-j4jv-cwfr

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
    <= 3.6.10>= 3.7.0-ea.1, < 3.7.0-ea.2
    Fixed in
    3.7.0-ea.2, 3.6.11

  • Go github.com/traefik/traefik/v2

    Affected
    <= 2.11.40
    Fixed in
    2.11.41

  • 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
6.3 · CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N · score source
EPSS
  • CVE-2026-32595: 0.39% estimated exploitation activity in the next 30 days; percentile 33.38 (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 potential vulnerability in Traefik's BasicAuth middleware that allows username enumeration via a timing attack. When a submitted username exists, the middleware performs a bcrypt password comparison taking ~166ms. When the username does not exist, the response returns immediately in ~0.6ms. This ~298x timing difference is observable over the network and allows an unauthenticated attacker to reliably distinguish valid from invalid usernames. Patches - https://github.com/traefik/traefik/releases/tag/v2.11.41 - https://github.com/traefik/traefik/releases/tag/v3.6.11 - https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.2 For more information If you have any questions or comments about this advisory, please open an issue. <details <summaryOriginal Description</summary Summary A timing attack vulnerability exists in Traefik's BasicAuth middleware that allows unauthenticated attackers to enumerate valid usernames. When a username exists, bcrypt password…

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

    Published from ghsa record GHSA-g3hg-j4jv-cwfr

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-32595

Advisory: Traefik Affected by BasicAuth Middleware Timing Attack Allows Username Enumeration
IDs: CVE-2026-32595, GHSA-g3hg-j4jv-cwfr
Record: https://patchnext.com/advisories/cve-2026-32595 (revision 1, source checked 26 Oct 2026, 15:18 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
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-ea.2, 3.6.11; github.com/traefik/traefik/v2 2.11.41. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/traefik/traefik/v3: affected <= 3.6.10; >= 3.7.0-ea.1, < 3.7.0-ea.2; fixed in 3.7.0-ea.2, 3.6.11
- Go github.com/traefik/traefik/v2: affected <= 2.11.40; fixed in 2.11.41
- 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://github.com/advisories/GHSA-g3hg-j4jv-cwfr (GitHub-reviewed advisory GHSA-g3hg-j4jv-cwfr lists affected ranges: Go github.com/traefik/traefik >=0 =0 =0 =3.7.0-ea.1 <3.7.0-ea.2)

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