FKIE_CVE-2026-66005

Vulnerability from fkie_nvd - Published: 2026-07-24 15:19 - Updated: 2026-10-24 13:10
Severity
6.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
Summary
Jan through 0.8.4, fixed in commit 3e1c1e7, contains a CORS misconfiguration vulnerability in its local API server that allows network-adjacent attackers to bypass trusted host restrictions by exploiting the server's replacement of user-configured trusted hosts with a wildcard that reflects arbitrary origins with credentials. Attackers on the local network or using DNS rebinding can reach the unauthenticated OpenAI-compatible API to perform inference, enumerate models, invoke MCP tools, and read cross-origin responses.
References
disclosure@vulncheck.comhttps://github.com/janhq/jan/commit/3e1c1e724f696620d89bb4a9cc18a380e0753757
disclosure@vulncheck.comhttps://github.com/janhq/jan/issues/8453
disclosure@vulncheck.comhttps://github.com/janhq/jan/pull/8506
disclosure@vulncheck.comhttps://www.vulncheck.com/advisories/jan-local-api-server-cors-origin-reflection-via-binding
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:github/janhq/jan",
          "product": "jan",
          "repo": "https://github.com/janhq/jan",
          "vendor": "janhq",
          "versions": [
            {
              "lessThanOrEqual": "0.8.4",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "3e1c1e724f696620d89bb4a9cc18a380e0753757",
              "versionType": "git"
            }
          ]
        }
      ],
      "source": "disclosure@vulncheck.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Jan through 0.8.4, fixed in commit 3e1c1e7, contains a CORS misconfiguration vulnerability in its local API server that allows network-adjacent attackers to bypass trusted host restrictions by exploiting the server\u0027s replacement of user-configured trusted hosts with a wildcard that reflects arbitrary origins with credentials. Attackers on the local network or using DNS rebinding can reach the unauthenticated OpenAI-compatible API to perform inference, enumerate models, invoke MCP tools, and read cross-origin responses."
    },
    {
      "lang": "es",
      "value": "Jan hasta la 0.8.4, corregida en el commit 3e1c1e7, contiene una vulnerabilidad de mala configuraci\u00f3n de CORS en su servidor API local que permite a atacantes adyacentes a la red eludir las restricciones de host de confianza explotando el reemplazo por parte del servidor de los hosts de confianza configurados por el usuario por un comod\u00edn que refleja or\u00edgenes arbitrarios con credenciales. Atacantes en la red local o que utilizan el reenlace de DNS pueden acceder a la API compatible con OpenAI no autenticada para realizar inferencia, enumerar modelos, invocar herramientas MCP y leer respuestas de origen cruzado."
    }
  ],
  "id": "CVE-2026-66005",
  "lastModified": "2026-10-24T13:10:00.147",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 3.4,
        "source": "disclosure@vulncheck.com",
        "type": "Secondary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "LOW",
          "vulnConfidentialityImpact": "LOW",
          "vulnIntegrityImpact": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "disclosure@vulncheck.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-66005",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-07-24T15:32:21.328068Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-24T15:19:07.203",
  "references": [
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/janhq/jan/commit/3e1c1e724f696620d89bb4a9cc18a380e0753757"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/janhq/jan/issues/8453"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://github.com/janhq/jan/pull/8506"
    },
    {
      "source": "disclosure@vulncheck.com",
      "url": "https://www.vulncheck.com/advisories/jan-local-api-server-cors-origin-reflection-via-binding"
    }
  ],
  "sourceIdentifier": "disclosure@vulncheck.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-183"
        },
        {
          "lang": "en",
          "value": "CWE-942"
        }
      ],
      "source": "disclosure@vulncheck.com",
      "type": "Secondary"
    }
  ]
}



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