CVE-2025-66491

Traefik is an HTTP reverse proxy and load balancer. Versions 3.5.0 through 3.6.2 have inverted TLS verification logic in the nginx.ingress.kubernetes.io/proxy-ssl-verify annotation. Setting the annotation to "on" (intending to enable backend TLS certificate verification) actually disables verification, allowing man-in-the-middle attacks against HTTPS backends when operators believe they are protected. This issue is fixed in version 3.6.3.

CVSS v3 5.9 MEDIUM

5.9^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.2 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4	Patch
https://github.com/traefik/traefik/releases/tag/v3.6.3	Release Notes
https://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vj	Patch Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*

History

14 Oct 2026, 22:10

Type	Values Removed	Values Added
Summary		(es) Traefik es un proxy inverso HTTP y un balanceador de carga. Las versiones 3.5.0 a 3.6.2 tienen la lógica de verificación TLS invertida en la anotación nginx.ingress.kubernetes.io/proxy-ssl-verify. Establecer la anotación en 'on' (con la intención de habilitar la verificación del certificado TLS del backend) en realidad deshabilita la verificación, permitiendo ataques man-in-the-middle contra backends HTTPS cuando los operadores creen que están protegidos. Este problema está solucionado en la versión 3.6.3.

Information

Published : 2025-12-09 01:16

Updated : 2026-10-14 22:10

NVD link : CVE-2025-66491

Mitre link : CVE-2025-66491

CVE.ORG link : CVE-2025-66491

JSON object : View

Products Affected

traefik

traefik

CWE

CWE-295

Improper Certificate Validation

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