Vulnerabilities
Projects
Vulnerability Disclosure
About Us
Contact Us
Mend.io Vulnerability Database
What is a CVE vulnerability ID? 
What is a WS vulnerability ID?
What is an MSC vulnerability ID?
New vulnerability? Tell us about it!
What is a WS vulnerability ID?
What is an MSC vulnerability ID?
We found results for “”
CVE-2025-66491
Good to know:
Date: December 8, 2025
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.
Severity Score
Related Resources (6)
Severity Score
Weakness Type (CWE)
Improper Certificate Validation
CWE-295Top Fix
Upgrade Version
Upgrade to version github.com/traefik/traefik/v3 - v3.6.3;https://github.com/traefik/traefik.git - v3.6.3
CVSS v3.1
| Base Score: |
|
|---|---|
| Attack Vector (AV): | NETWORK |
| Attack Complexity (AC): | HIGH |
| Privileges Required (PR): | NONE |
| User Interaction (UI): | NONE |
| Scope (S): | UNCHANGED |
| Confidentiality (C): | HIGH |
| Integrity (I): | NONE |
| Availability (A): | NONE |