by Kastro
Paper/Archive/CVE-2026-85597

CVE-2026-85597

traefik traefik — Traefik before v2.11.55 and v3.0.0 through v3.7.10 mTLS Bypass via TLS Option Conflict

EPSS 0.4%CVSS 9.1
critical.is priorityof 100
33
CVSS 9.1 (NVD)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 28.7.287 × 205.7No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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

ProductAffectedFixed inSource
traefik< 2.11.552.11.55CNA
traefik3.0.0 – 3.7.10–CNA

Scores by source

NVD9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
VulnCheck (CNA)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
CISA ADPSSVCExploitation: none · Automatable: no · Technical impact: partial

References

advisorygithub.com/traefik/traefik/security/advisories/GHSA-g55h-rg46-x9c5writeupvulncheck.com/advisories/traefik-before-2.11.55-mtls-bypass-via-tls-option-conflict