---
id: "CVE-2026-114656"
kind: "vulnerability"
aliases: ["CVE-2026-114656"]
title: "Traefik: negated Host rules let clients skip client-certificate checks"
severity: "high"
cvss: 7.5
epss: 0.00163
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "kubernetes", "mtls", "self-hosted", "traefik"]
not_affected_if: ["no-client-cert-auth", "no-negated-host-rules", "patched-version"]
published_at: "2026-10-22T02:16:57+00:00"
first_seen_at: "2026-10-23T21:57:30+00:00"
updated_at: "2026-10-25T03:16:18+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-114656", "first_seen_at": "2026-10-23T21:57:30+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-114656", "first_seen_at": "2026-10-24T07:15:52+00:00"}]
---

# Traefik: negated Host rules let clients skip client-certificate checks

Traefik before 2.11.58 and 3.7.13 counts negated Host matchers as served domains, which can create a TLS options conflict that falls back to default options. An unauthenticated client can then reach backends that were meant to require verified client certificates.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `traefik version` (or check the container image tag) and compare against `2.11.58` and `3.7.13`
- Look for routers using `!Host(` rules alongside `RequireAndVerifyClientCert` TLS options in the dynamic configuration
- unknown whether other specific configurations are exposed

## Fix

- Upgrade Traefik 2.x to `2.11.58` or later
- Upgrade Traefik 3.x to `3.7.13` or later
- Until patched, remove negated `!Host()` router rules on routes protected by client-certificate verification (unknown whether this fully mitigates)

## Timeline

- 2026-10-23T21:57:30+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-114656
- 2026-10-24T07:15:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-114656

## From the sources

Traefik before 2.11.58 and 3.7.13 contains an authentication bypass vulnerability that allows unauthenticated clients to skip client-certificate checks because negated Host matchers are counted as served domains. Attackers can reach backends protected by RequireAndVerifyClientCert when a router rule with !Host() creates a TLS options conflict that falls back to the default options.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_