Improper access control in Traefik - #VU144552
Published: August 21, 2026
Vulnerability identifier: #VU144552
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass client-certificate authentication and access a protected backend.
The vulnerability exists due to improper access control in TLS options conflict resolution for multi-host routers when handling TLS handshakes for overlapping host rules with different TLS options. A remote attacker can connect to a protected hostname without a client certificate to bypass client-certificate authentication and access a protected backend.
The issue is limited to configurations where a multi-host router overlaps another router with a different TLS option for only one of its hostnames.
Affected software
Traefik
Remediation
Install security update from vendor's website.
Traefik - addressed in versions 2.11.55, 3.7.11