Medium 5.9Published Dec 9, 2025

CVE-2025-66491Traefik is an HTTP reverse proxy and load balancer.

Updated under an hour ago (2026-10-19 08:23 UTC)

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It affects traefik. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for traefik

Exploited in the last 30 days

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: 5.9 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness (CWE): CWE-295
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Analyzed
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

traefik traefik traefik:traefik	from 3.5.0 before 3.6.3	NVD

References

https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4patch
https://github.com/traefik/traefik/releases/tag/v3.6.3release-notes
https://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vjpatch, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.