Vulnerability · Published Sep 4, 2026 · Assigned by VulnCheck

CVE-2026-85597Traefik before v2.11.55 and v3.0.0 through v3.7.10 mTLS Bypass via TLS Option Conflict

High 8.2

In plain English

A high-severity incorrect authorization in traefik from traefik. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities).

Severity (CVSS 4.0)8.2High

Exploit odds (30 days)0.4%top 71.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Traefik before v2.11.55 and v3.0.0 through v3.7.10 contain a TLS option conflict resolution vulnerability that allows unauthenticated attackers to bypass client-certificate authentication by creating conflicting TLS options on multi-host routers. Attackers can reach protected backends by exploiting shared TLS resolution across multiple hostnames in a single router rule, causing the strict mTLS requirement to fall back to default options for all hosts.

Affected products (as reported)

Vendor	Product	Versions
traefik	traefik	0 – before 2.11.55
traefik	traefik	3.0.0 – through 3.7.10

Weakness: CWE-863 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

References

GitHub Security Advisory (GHSA-g55h-rg46-x9c5) vendor-advisory
VulnCheck Advisory: Traefik before v2.11.55 mTLS Bypass via TLS Option Conflict third-party-advisory