Authentication Bypass by Primary Weakness in Traefik - CVE-2026-32305
Published: May 5, 2026
Vulnerability identifier: #VU129669
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-32305
CWE-ID: CWE-305
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass mutual TLS authentication and access services protected by route-level mTLS.
The vulnerability exists due to improper security decision based on incomplete input in TLS SNI pre-sniffing logic when processing fragmented TLS ClientHello records. A remote attacker can send a specially crafted fragmented ClientHello to bypass mutual TLS authentication and access services protected by route-level mTLS.
Exploitation requires route-level TLS options to enforce mTLS for a host while the default TLS configuration is weaker and pre-sniff SNI extraction fails with an empty SNI.
Affected software
Traefik
How to mitigate CVE-2026-32305
Install security update from vendor's website.
Traefik - addressed in versions 2.11.41, 3.6.11