CVE-2026-48491
Traefik: Traefik: Unauthorized access due to mutual TLS bypass
Severity by source
Trivy's own label is CRITICAL. Rated critical by NVD. Rated lower by GHSA (high), Red Hat (high).
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 packages and fixed versions
| Source | Package | Fixed in |
|---|---|---|
| alpine edge | traefik | 3.7.7-r0 |
| go::GitHub Security Advisory Go | github.com/traefik/traefik/v2, github.com/traefik/traefik/v3 | 2.11.48 and 1 more |
| minimos | traefik-3, traefik-fips-3 | 3.7.3-r0 |
| rapidfort alpine 3.20 | traefik | 3.7.7-r0 |
| rapidfort alpine 3.21 | traefik | 3.7.7-r0 |
| rapidfort alpine 3.22 | traefik | 3.7.7-r0 |
| rapidfort alpine 3.23 | traefik | 3.7.7-r0 |
| rapidfort alpine 3.24 | traefik | 3.7.7-r0 |
Show all 10 entries from 8 sources
| Source | Package | Fixed in |
|---|---|---|
| alpine edge | traefik | 3.7.7-r0 |
| go::GitHub Security Advisory Go | github.com/traefik/traefik/v2 | 2.11.48 |
| go::GitHub Security Advisory Go | github.com/traefik/traefik/v3 | 3.7.3 |
| minimos | traefik-3 | 3.7.3-r0 |
| minimos | traefik-fips-3 | 3.7.3-r0 |
| rapidfort alpine 3.20 | traefik | 3.7.7-r0 |
| rapidfort alpine 3.21 | traefik | 3.7.7-r0 |
| rapidfort alpine 3.22 | traefik | 3.7.7-r0 |
| rapidfort alpine 3.23 | traefik | 3.7.7-r0 |
| rapidfort alpine 3.24 | traefik | 3.7.7-r0 |
References
- https://access.redhat.com/errata/RHSA-2026:62260
- https://access.redhat.com/security/cve/CVE-2026-48491
- https://bugzilla.redhat.com/show_bug.cgi?id=2491923
- https://github.com/traefik/traefik
- https://github.com/traefik/traefik/releases/tag/v2.11.48
- https://github.com/traefik/traefik/releases/tag/v3.6.19
- https://github.com/traefik/traefik/releases/tag/v3.7.3
- https://github.com/traefik/traefik/security/advisories/GHSA-5r4w-85f3-pw66