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7.8 High

CVE-2026-48491 Traefik is an HTTP reverse proxy and load balancer

Description

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.

Affected products and versions

Product Affected versions Fixed in
traefik 3.7 3.7.0 → < 3.7.3 3.7.3
Red Hat OpenShift Dev Spaces Versions not published
Red Hat OpenShift Dev Spaces 3.30 1787756799 earliest → < 1787756799 1787756799

References

Timeline

  1. Published
  2. Last modified

Other CVEs of traefik

The 80 CVEs of traefik →
CVE-2026-121966 Traefik before 2.11.60 and 3.7.16 ForwardAuth NTLM/Negotiate Identity Leak 7.0 High CVE-2026-119574 Traefik from 3.2.0 before 3.7.15 contains a data race in the experimental FastProxy that allows unauthenticated… 8.2 High CVE-2026-119573 Traefik 3.7.11 before 3.7.15 contains an authorization bypass in the Kubernetes Ingress NGINX provider that skips the… 2.1 Low CVE-2026-119572 Traefik 3.7.0-ea.1 before 3.7.15 mTLS Bypass via Ingress NGINX Provider 7.0 High
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