CVE-2026-48491

Traefik is an HTTP reverse proxy and load balancer. From 3.7.0 until 3.7.3, there is a high severity vulnerability in Traefik's domain-fronting protection (SNICheck) that allows an unauthenticated client to bypass mutual TLS enforced through wildcard router TLSOptions. When a router uses a wildcard host rule such as Host(*.example.com) with stricter TLS options (for example RequireAndVerifyClientCert), SNICheck resolves the TLS options for the HTTP Host header using exact map lookups only and never applies wildcard matching. If another permissive SNI is served on the same entrypoint, an attacker can complete the TLS handshake under the permissive options and then send an HTTP Host header targeting the wildcard-protected backend, reaching it without presenting a client certificate. This affects the regular HTTPS / HTTP-2 path and does not require HTTP/3. This vulnerability is fixed in 3.7.3.

CVSS

No CVSS.

References

Link	Resource
https://github.com/traefik/traefik/releases/tag/v3.7.3
https://github.com/traefik/traefik/security/advisories/GHSA-5r4w-85f3-pw66

Configurations

No configuration.

History

23 Jun 2026, 20:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-06-23 20:16

Updated : 2026-06-24 16:16

NVD link : CVE-2026-48491

Mitre link : CVE-2026-48491

CVE.ORG link : CVE-2026-48491

JSON object : View

Products Affected

No product.

CWE

CWE-288

Authentication Bypass Using an Alternate Path or Channel

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