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.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-7vww-mvcr-x6vj Traefik Inverted TLS Verification Logic in ingress-nginx Provider
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Fri, 02 Jan 2026 21:15:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*

Wed, 10 Dec 2025 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Tue, 09 Dec 2025 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 09 Dec 2025 10:15:00 +0000

Type Values Removed Values Added
First Time appeared Traefik
Traefik traefik
Vendors & Products Traefik
Traefik traefik

Tue, 09 Dec 2025 00:45:00 +0000

Type Values Removed Values Added
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.
Title Traefik has Inverted TLS Verification Logic in its ingress-nginx Provider
Weaknesses CWE-295
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2025-12-09T16:03:28.511Z

Reserved: 2025-12-02T22:44:04.707Z

Link: CVE-2025-66491

cve-icon Vulnrichment

Updated: 2025-12-09T14:17:32.518Z

cve-icon NVD

Status : Analyzed

Published: 2025-12-09T01:16:55.720

Modified: 2026-01-02T21:12:07.183

Link: CVE-2025-66491

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-12-09T00:38:39Z

Links: CVE-2025-66491 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-12-09T10:04:39Z

Weaknesses