Traefik incorrectly processes fragment in the URL, leads to Authorization Bypass

Exploitation

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

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS

• CVE-2023-47106: 0.63% estimated exploitation activity in the next 30 days; percentile 50.05 (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 When a request is sent to Traefik with a URL fragment, Traefik automatically URL encodes and forwards the fragment to the backend server. This violates the RFC because in the origin-form the URL should only contain the absolute path and the query. When this is combined with another frontend proxy like Nginx, it can be used to bypass frontend proxy URI-based access control restrictions. Details For example, we have this Nginx configuration: This can be bypassed when the attacker is requesting to /#/../admin This won’t be vulnerable if the backend server follows the RFC and ignores any characters after the fragment. However, if Nginx is chained with another reverse proxy which automatically URL encode the character

(Traefik) the URL will become /%23/../admin And allow the attacker to completely bypass the Access Restriction from the Nginx Front-End proxy. Here is a diagram to summarize the attack: PoC This is the POC docker I've set up. It contains Nginx, Traefik proxies and…

Published by the source

5 Dec 2023, 18:11 UTC

Last modified by the source

7 Dec 2023, 23:06 UTC

Source last checked

26 Oct 2026, 15:00 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fvhj-4qfh-q2hm

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# Patch Next advisory brief: CVE-2023-47106

Advisory: Traefik incorrectly processes fragment in the URL, leads to Authorization Bypass
IDs: CVE-2023-47106, GHSA-fvhj-4qfh-q2hm
Record: https://patchnext.com/advisories/cve-2023-47106 (revision 1, source checked 26 Oct 2026, 15:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
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 3.0.0-beta5; github.com/traefik/traefik/v2 2.10.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/traefik/traefik/v3: affected < 3.0.0-beta5; fixed in 3.0.0-beta5
- Go github.com/traefik/traefik/v2: affected < 2.10.6; fixed in 2.10.6

## 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-fvhj-4qfh-q2hm (GitHub-reviewed advisory GHSA-fvhj-4qfh-q2hm lists affected ranges: Go github.com/traefik/traefik/v2 >=0 =0 <3.0.0-beta5)

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