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CVE-2025-66491

Traefik has Inverted TLS Verification Logic in its ingress-nginx Provider

Published: Dec 9, 2025Updated: Jan 2, 2026 Sources: CVE List NVD GHSACWE-295
NVD MITRE
5.9CVSSMEDIUM
EPSS Score
0.2%
Top 89.5%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:HPR:NUI:NS:UC:HI:NA:N
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:NIntegrity
None
A:NAvailability
None
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Weaknesses

CWE-295

Affected Products

traefiktraefik
On-prem
Networking Infrastructure / load-balancer-proxy
github.com/traefik/traefik/v3GoOSS Libraries
traefikoss-projectNetworking Infrastructureaka traefik enterprise
gopackage-ecosystemOSS Libraries

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Collection
View detailed technique mapping

References

https://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vj
github.com
https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4
github.com
https://github.com/traefik/traefik/releases/tag/v3.6.3
github.com
and 2 more references View all →

Timeline

Published
Dec 9, 2025
Last Updated
Jan 2, 2026

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