CVE-2026-32305
Description
Traefik is an HTTP reverse proxy and load balancer. Versions 2.11.40 and below, 3.0.0-beta1 through 3.6.11, and 3.7.0-ea.1 are vulnerable to mTLS bypass through the TLS SNI pre-sniffing logic related to fragmented ClientHello packets. When a TLS ClientHello is fragmented across multiple records, Traefik's SNI extraction may fail with an EOF and return an empty SNI. The TCP router then falls back to the default TLS configuration, which does not require client certificates by default. This allows an attacker to bypass route-level mTLS enforcement and access services that should require mutual TLS authentication. This issue is patched in versions 2.11.41, 3.6.11 and 3.7.0-ea.2.
How to fix
- traefik traefik2.11.41 or later
- github.com/traefik/traefik/v33.7.0-ea.2, 3.6.11 or later
- github.com/traefik/traefik/v22.11.41 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| traefik traefik | v < 2.11.41, 3.0.0 ≤ v ≤ 3.6.11, 3.7.0 | 2.11.41 |
| github.com/traefik/traefik/v3Go | 3.7.0-ea.1 ≤ v < 3.7.0-ea.2, v < 3.6.11 | 3.7.0-ea.2, 3.6.11 |
| github.com/traefik/traefik/v2Go | v < 2.11.41 | 2.11.41 |
| github.com/traefik/traefikGo | v ≤ 1.7.34, No range specified | — |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.