by Kastro
Paper/Archive/CVE-2026-85594

CVE-2026-85594

traefik traefik — Traefik v3.7.1 crossProviderNamespaces Bypass via Service Middleware

EPSS 0.5%CVSS 9.8
critical.is priorityof 100
38
CVSS 9.8 (NVD)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 41.1.411 × 208.2No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

Traefik versions from v3.7.1 fail to enforce crossProviderNamespaces restrictions on the traefik.ingress.kubernetes.io/service.middlewares Service annotation in the Kubernetes Ingress provider. A namespace-limited tenant excluded from the allowlist can attach an operator-owned middleware to its Service, and if that middleware injects backend credentials, recover them at a controlled backend.

Affected

ProductAffectedFixed inSource
traefik3.7.1 – 3.7.12–CNA

Scores by source

NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
VulnCheck (CNA)7.0CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: partial

References

advisorygithub.com/traefik/traefik/security/advisories/GHSA-m6wx-622r-48r9writeupvulncheck.com/advisories/traefik-3.7.1-crossprovidernamespaces-bypass-via-service-middleware