CVE-2026-48491
Critical · 10.0CVSS
10.0
EPSS
0.4%
Published
Jun 23, 2026
CISA due date
—
The record
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 packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| openSUSE:Tumbleweed | traefik | 0 | 3.7.5-1.1 |
Related vulnerabilities
- CVE-2026-53622 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-48020 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-44774 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-41181 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-41174 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-41263 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-35051 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
- CVE-2026-39858 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik