FKIE_CVE-2025-66491

Vulnerability from fkie_nvd - Published: 2025-12-09 01:16 - Updated: 2026-10-14 22:10
Severity
5.9 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
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.
References
security-advisories@github.comhttps://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4Patch
security-advisories@github.comhttps://github.com/traefik/traefik/releases/tag/v3.6.3Release Notes
security-advisories@github.comhttps://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vjPatch, Vendor Advisory
Impacted products
Vendor Product Version
traefik traefik *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "traefik",
          "vendor": "traefik",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 3.5.0, \u003c 3.6.3"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "C2211A70-8944-46AA-B318-B3669174DBCE",
              "versionEndExcluding": "3.6.3",
              "versionStartIncluding": "3.5.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "Traefik es un proxy inverso HTTP y un balanceador de carga. Las versiones 3.5.0 a 3.6.2 tienen la l\u00f3gica de verificaci\u00f3n TLS invertida en la anotaci\u00f3n nginx.ingress.kubernetes.io/proxy-ssl-verify. Establecer la anotaci\u00f3n en \u0027on\u0027 (con la intenci\u00f3n de habilitar la verificaci\u00f3n del certificado TLS del backend) en realidad deshabilita la verificaci\u00f3n, permitiendo ataques man-in-the-middle contra backends HTTPS cuando los operadores creen que est\u00e1n protegidos. Este problema est\u00e1 solucionado en la versi\u00f3n 3.6.3."
    }
  ],
  "id": "CVE-2025-66491",
  "lastModified": "2026-10-14T22:10:00.210",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.9,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2025-66491",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2025-12-09T14:17:29.439457Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2025-12-09T01:16:55.720",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://github.com/traefik/traefik/releases/tag/v3.6.3"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch",
        "Vendor Advisory"
      ],
      "url": "https://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vj"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-295"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}



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