CVE-2022-23632

Traefik skips the router TLS configuration when the host header is an FQDN

Published Feb 17, 2022 CVSS 3.1 · 7.4 High EPSS 1.7% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2022-1054 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.
Github GHSA Github GHSA GHSA-hrhx-6h34-j5hc Skip the router TLS configuration when the host header is an FQDN
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Apr 23, 2025, 7:02 PM
Reserved
Jan 19, 2022, 12:00 AM
Status
Modified
Published
Feb 17, 2022, 3:15 PM
Modified
Jun 17, 2026, 4:30 AM