Critical severity · published Sep 4, 2026
CVE-2026-85597
Traefik before v2.11.55 and v3.0.0 through v3.7.10 mTLS Bypass via TLS Option Conflict
9.1
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 29% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
TR
traefik · traefik
before 2.11.55; 3.0.0 through 3.7.10 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-85597
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-85597
vendor-advisory
https://github.com/traefik/traefik/security/advisories/GHSA-g55h-rg46-x9c5
third-party-advisory
https://www.vulncheck.com/advisories/traefik-before-2.11.55-mtls-bypass-via-tls-option-conflict
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