Traefik has a StripPrefix Route-Level Auth Bypass via Path Normalization

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.8 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N · score source

EPSS

• CVE-2026-48020: 0.78% estimated exploitation activity in the next 30 days; percentile 55.83 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary There is a high severity vulnerability in Traefik's StripPrefix middleware that allows an unauthenticated attacker to bypass route-level authentication and authorization. When a public router matches on a PathPrefix rule and applies the StripPrefix middleware, a request path containing .. or its percent-encoded form %2e%2e can match the public route at routing time and then, after the prefix is stripped and the path is normalized, resolve to a path served by a separate, authenticated router. As a result, an attacker can reach protected backend paths — such as admin or internal configuration endpoints — without satisfying the authentication middleware attached to the protected router. Patches - https://github.com/traefik/traefik/releases/tag/v2.11.48 - https://github.com/traefik/traefik/releases/tag/v3.6.19 - https://github.com/traefik/traefik/releases/tag/v3.7.3 For more information If there are any questions or comments about this advisory, please open an issue. <details…

Published by the source

11 Jun 2026, 13:26 UTC

Last modified by the source

2 Sep 2026, 15:34 UTC

Source last checked

26 Oct 2026, 15:28 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-xf64-8mw2-4gr2

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# Patch Next advisory brief: CVE-2026-48020

Advisory: Traefik has a StripPrefix Route-Level Auth Bypass via Path Normalization
IDs: CVE-2026-48020, GHSA-xf64-8mw2-4gr2
Record: https://patchnext.com/advisories/cve-2026-48020 (revision 1, 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: High (CVSS 7.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/traefik/traefik/v3 3.7.3, 3.6.19; github.com/traefik/traefik/v2 2.11.48. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/traefik/traefik/v3: affected < 3.6.19; >= 3.7.0-ea.1, < 3.7.3; fixed in 3.6.19, 3.7.3
- Go github.com/traefik/traefik/v2: affected < 2.11.48; fixed in 2.11.48

## 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.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## 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.
- 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-xf64-8mw2-4gr2 (GitHub-reviewed advisory GHSA-xf64-8mw2-4gr2 lists affected ranges: Go github.com/traefik/traefik/v2 >=0 =0 =3.7.0-ea.1 <3.7.3)

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