Critical severity · published Sep 4, 2026
CVE-2026-85594
Traefik v3.7.1 crossProviderNamespaces Bypass via Service Middleware
9.8
CVSS
0.5%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 41% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
TR
traefik · traefik
3.7.1 through 3.7.12 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-85594
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-85594
vendor-advisory
https://github.com/traefik/traefik/security/advisories/GHSA-m6wx-622r-48r9
third-party-advisory
https://www.vulncheck.com/advisories/traefik-3.7.1-crossprovidernamespaces-bypass-via-service-middleware
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