---
title: "CVE-2026-88008: Traefik - Authentication Bypass"
description: "Traefik 2.11.26 to 2.11.57 and 3.7.13 contain an authentication bypass caused by forwarding client-supplied Upgrade headers to backends supporting h2c, letting unauthenticated attackers access protected routes, exploit requires backend accepting h2c and returning 101 Switching Protocols."
url: https://panop.io/threat-heartbeat/CVE-2026-88008/
---

# CVE-2026-88008 Traefik - Authentication Bypass

Traefik 2.11.26 to 2.11.57 and 3.7.13 contain an authentication bypass caused by forwarding client-supplied Upgrade headers to backends supporting h2c, letting unauthenticated attackers access protected routes, exploit requires backend accepting h2c and returning 101 Switching Protocols.

CVSS base score 9.1 /10

Critical

CISA KEV

Not listed

Public exploit

Proof of concept available

EPSS

0.49% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-88008)

## Details

Type

Authentication Bypass

Impact

Broken Access Control

CVSS vector

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

Published

10 September 2026

Updated

15 October 2026

Weakness

[CWE-444](https://cwe.mitre.org/data/definitions/444.html)

## Vendor fix

Upgrade to versions 2.11.57 or 3.7.13 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-88008](https://nvd.nist.gov/vuln/detail/CVE-2026-88008)
- [https://github.com/traefik/traefik/releases/tag/v2.11.57](https://github.com/traefik/traefik/releases/tag/v2.11.57)
- [https://github.com/traefik/traefik/releases/tag/v3.7.13](https://github.com/traefik/traefik/releases/tag/v3.7.13)
- [https://github.com/traefik/traefik/security/advisories/GHSA-w4v4-9rw7-5326](https://github.com/traefik/traefik/security/advisories/GHSA-w4v4-9rw7-5326)
- [https://github.com/traefik/traefik/commit/a277e94664ffc1ce9543df552d3bbf48d4d3b8b3](https://github.com/traefik/traefik/commit/a277e94664ffc1ce9543df552d3bbf48d4d3b8b3)
- [https://github.com/traefik/traefik/pull/13797](https://github.com/traefik/traefik/pull/13797)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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