CVE-2026-85597

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 4.0

8.2CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS 3.1

9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS

0.4% chance of exploitation in the next 30 days; higher than 28% of CVEs (scores of 2026-10-25)

CWE

CWE-863

Published

2026-09-04

Modified

2026-10-08

Record from

the NVD, synced 2026-10-19

Affected

• traefik:traefik

References

• https://github.com/traefik/traefik/security/advisories/GHSA-g55h-rg46-x9c5
• https://www.vulncheck.com/advisories/traefik-before-2.11.55-mtls-bypass-via-tls-option-conflict

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