CVE-2026-74905

{
  "id": "CVE-2026-74905",
  "sourceIdentifier": "[email protected]",
  "published": "2026-08-18T12:19:30.780",
  "lastModified": "2026-10-22T22:10:00.250",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "SiYuan before v3.7.4 contains a server-side request forgery (SSRF) vulnerability in the isPrivateIP function in kernel/util/net.go, used by SSRFSafeDialer to enforce SSRF protection in SafeMode. The function only checks for loopback, link-local unicast, private, and unspecified addresses and does not recognize IPv6 transition addresses (NAT64 64:ff9b::/96, 6to4 2002::/16, Teredo 2001::/32) that embed private IPv4 destinations. When SafeMode is enabled, an authenticated attacker can bypass the SSRF guard via the network forward proxy, WebSocket proxy, or SSE proxy endpoints by supplying a URL whose hostname resolves to such a transition address, reaching internal services and cloud metadata endpoints (e.g., 169.254.169.254). Because the forward proxy returns the full response body, this is a full-read SSRF that can be used to steal instance credentials, reach internal services, and port-scan internal infrastructure."
    },
    {
      "lang": "es",
      "value": "SiYuan antes de la v3.7.4 contiene una vulnerabilidad de falsificación de petición del lado del servidor (SSRF) en la función isPrivateIP en kernel/util/net.go, utilizada por SSRFSafeDialer para aplicar la protección SSRF en SafeMode. La función solo verifica direcciones de bucle invertido, unicast de enlace local, privadas y no especificadas y no reconoce direcciones de transición IPv6 (NAT64 64:ff9b::/96, 6to4 2002::/16, Teredo 2001::/32) que incrustan destinos IPv4 privados. Cuando SafeMode está habilitado, un atacante autenticado puede eludir la protección SSRF a través de los puntos finales del proxy de reenvío de red, proxy WebSocket o proxy SSE al proporcionar una URL cuyo nombre de host se resuelve en una dirección de transición de este tipo, alcanzando servicios internos y puntos finales de metadatos en la nube (p. ej., 169.254.169.254). Debido a que el proxy de reenvío devuelve el cuerpo completo de la respuesta, esto es una SSRF de lectura completa que puede utilizarse para robar credenciales de instancia, alcanzar servicios internos y escanear puertos de la infraestructura interna."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "siyuan-note",
          "product": "siyuan",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "0",
              "lessThan": "3.7.4",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "3.7.4",
              "versionType": "semver",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV40": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "4.0",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L/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",
          "baseScore": 6.9,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "LOW",
          "vulnAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "LOW",
          "subIntegrityImpact": "LOW",
          "subAvailabilityImpact": "LOW",
          "exploitMaturity": "NOT_DEFINED",
          "confidentialityRequirement": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "valueDensity": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N",
          "baseScore": 7.1,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "LOW",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 4.2
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-08-19T14:09:42.098446Z",
          "id": "CVE-2026-74905",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-918"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-qq8m-8p8v-x4xg",
      "source": "[email protected]"
    },
    {
      "url": "https://www.vulncheck.com/advisories/siyuan-before-ssrf-via-ipv6-transition-address-bypass",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-qq8m-8p8v-x4xg",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    }
  ]
}