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TI-2025-40915 Aliases CVE-2025-66491GHSA-7vww-mvcr-x6vj

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

Priority LOW 26CWE-295Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
Spoofing
Confidentiality · integrity · availability
High · None · None
Fix status
Partial Red Hat: 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-295.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00221 12th percentileScored 2026-11-07
Fix Partial traefik (traefik): 3.6.3github.com/traefik/traefik/v3 (Go): 3.6.3Red Hat: 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
traefiktraefik3.5.0 to before 3.6.33.6.3Patch availableCNA
—github.com/traefik/traefik/v3 (Go)3.5.0 to before 3.6.33.6.3Patch availableGHSA-7vww-mvcr-x6vj
  • traefik Vendortraefik Affected 3.5.0 to before 3.6.3 Fixed in 3.6.3 Patch available CNA
  • github.com/traefik/traefik/v3 (Go) Vendor— Affected 3.5.0 to before 3.6.3 Fixed in 3.6.3 Patch available GHSA-7vww-mvcr-x6vj

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*3.5.0 to before 3.6.3Vulnerabletraefik
  • cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:* Versions 3.5.0 to before 3.6.3 Vulnerable ·traefik

Remediation

  • Fix · CNA traefik (traefik) Fixed in 3.6.3
  • Fix · GHSA-7vww-mvcr-x6vj github.com/traefik/traefik/v3 (Go) Fixed in 3.6.3 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat OpenShift Dev SpacesAffectedNo fix yet: Fix deferred

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-66491
  2. 2026-10-03 Alias added: GHSA-7vww-mvcr-x6vj

References

Patch 2

Advisory 1

Other 2

  • TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
  • TI-2023-25774 Uncontrolled Resource Consumption in Traefik CVSS 3.1HIGH 7.5
  • TI-2025-40914 Traefik doesn't Prevent Path Normalization Bypass in Router + Middleware Rules CVSS 4.0MEDIUM 6.9
  • TI-2022-07529 Authorization header displayed in the debug logs CVSS 3.1MEDIUM 6.5
  • TI-2024-30459 HTTP client can remove the X-Forwarded headers in Traefik CVSS 3.1CRITICAL 9.8
  • TI-2026-60261 Traefik v3.7.0 Authentication Bypass via from-to-www-redirect CVSS 4.0CRITICAL 9.3
See all 83 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences