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Authentication Bypass Affecting traefik-3 package, versions <3.7.3-r0

Severity

 Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.28% (21st percentile)

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  • Snyk IDSNYK-MINIMOSLATEST-TRAEFIK3-18741871
  • published13 Aug 2026
  • disclosed23 Jun 2026
Report a new vulnerability Found a mistake?

Introduced: 23 Jun 2026

CVE-2026-48491  (opens in a new tab)
CWE-288  (opens in a new tab)

How to fix?

Upgrade Minimos:latest traefik-3 to version 3.7.3-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream traefik-3 package and not the traefik-3 package as distributed by Minimos. See How to fix? for Minimos:latest relevant fixed versions and status.

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.