CVE-2026-121966

{
  "etk_id": "ETK-2026-3517",
  "cve_id": "CVE-2026-121966",
  "display_id": "CVE-2026-121966",
  "ghsa_id": "GHSA-hrpp-p4fc-wwf8",
  "euvd_id": "EUVD-2026-116966",
  "status": "published",
  "anchor_state": "anchored",
  "title": "Cross-user authentication connection reuse in Traefik",
  "summary": "Traefik versions before 2.11.60 in the 2.x line and before 3.7.16 in the 3.x line can improperly reuse authenticated connections to ForwardAuth services; the affected 3.7 behavior also includes Ingress NGINX auth-url handling. An unauthenticated attacker may gain access to protected backends under another user's identity when the authentication service relies on connection-bound NTLM or Negotiate authentication.",
  "mitigation": "Upgrade Traefik 2.x to 2.11.60 or later, or Traefik 3.x to 3.7.16 or later. Until upgraded, reduce exposure by avoiding connection-bound NTLM or Negotiate authentication on affected external-authentication paths.",
  "vendor": "traefik",
  "product": "traefik",
  "affected": [
    {
      "affected_notes": [],
      "affected_ranges": [
        "<= v2.11.59"
      ],
      "ecosystem": "go",
      "fixed_versions": [
        "v2.11.60"
      ],
      "package_name": "github.com/traefik/traefik/v2",
      "purl": "pkg:golang/github.com/traefik/traefik/v2"
    },
    {
      "affected_notes": [],
      "affected_ranges": [
        ">= v3.0.0, <= v3.7.15"
      ],
      "ecosystem": "go",
      "fixed_versions": [
        "v3.7.16"
      ],
      "package_name": "github.com/traefik/traefik/v3",
      "purl": "pkg:golang/github.com/traefik/traefik/v3"
    }
  ],
  "cwes": [
    488
  ],
  "cvss_score": 7,
  "cvss_src": "cna_vendor",
  "cvss_vector": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N",
  "epss_score": null,
  "epss_percentile": null,
  "epss_asof": null,
  "automation": "contextual",
  "check": false,
  "check_confidence_basis": null,
  "exploit": false,
  "pipeline_minutes": 9.485854183333334,
  "t0_at": "2026-11-04T15:33:28.106000+00:00",
  "signals": {
    "trigger_signal": {
      "at": "2026-11-04T15:33:28.106000+00:00",
      "days": 0,
      "is_lower_bound": false,
      "measured_at": "2026-11-04T15:33:28.106000+00:00",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-121966"
    }
  }
}