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CVE-2025-66491

nvd nist
Published: Dec 9, 2025Modified: Jun 17, 2026

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5.9
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Exploitability: 2.2 / Impact: 3.6
Source: security-advisories@github.com (Secondary)

Description

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.

Affected (1)

Products: Traefik: Traefik
1 product
Traefik
Configuration A
1 vulnerable
Vulnerable SoftwareAffected Versions
From 3.5.0 to 3.6.3

References (3)

Source: security-advisories@github.com
Release Notes
Source: security-advisories@github.com
PatchVendor Advisory

Timeline

No history available yet.