CVE-2025-66491
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 3.1
- 5.9
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - EPSS
- 0.2% chance of exploitation in the next 30 days; higher than 12% of CVEs (scores of 2026-10-25)
- CWE
- CWE-295
- Published
- Modified
- Record from
- the NVD, synced
Affected
- traefik:traefik
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-7vww-mvcr-x6vj | Go | github.com/traefik/traefik/v3 | >=3.5.0 <3.6.3 | 3.6.3 |
| GO-2025-4205 | Go | github.com/traefik/traefik | all versions | no fix published |
| GO-2025-4205 | Go | github.com/traefik/traefik/v2 | all versions | no fix published |
| GO-2025-4205 | Go | github.com/traefik/traefik/v3 | >=3.5.0 <3.6.3 | 3.6.3 |