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CVE-2026-32305

CVE-2026-32305 · Traefik mTLS bypass via fragmented ClientHello SNI extraction failure

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 7.8 · High · EPSS 0.4%

Published
Updated

Stack: web

Affected products and versions

  • traefik

    Versions
    • < 2.11.41: Affected
    • >= 3.0.0-beta1, < 3.6.11: Affected
    • >= 3.7.0-ea.1, < 3.7.0-ea.2: Affected

    No fix published

Original sources

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