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CVE-2020-29479

Status: ModifiedHigh (8.8)—

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (3)

Debian — Debian LinuxFedoraproject — FedoraXEN — XEN

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2020-29479",
  "cveTags": [],
  "metrics": {
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        "source": "nvd@nist.gov",
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          "baseScore": 7.2,
          "accessVector": "LOCAL",
          "vectorString": "AV:L/AC:L/Au:N/C:C/I:C/A:C",
          "authentication": "NONE",
          "integrityImpact": "COMPLETE",
          "accessComplexity": "LOW",
          "availabilityImpact": "COMPLETE",
          "confidentialityImpact": "COMPLETE"
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        "acInsufInfo": false,
        "impactScore": 10,
        "baseSeverity": "HIGH",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 3.9,
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          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
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        "impactScore": 6,
        "exploitabilityScore": 2
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  "affected": [
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      "affectedData": [
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          "product": "n/a",
          "versions": [
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              "version": "n/a"
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  "published": "2020-12-15T18:15:14.897",
  "references": [
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      "source": "cve@mitre.org"
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      "source": "cve@mitre.org"
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
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  "vulnStatus": "Modified",
  "weaknesses": [
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      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-862"
        }
      ]
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  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable."
    },
    {
      "lang": "es",
      "value": "Se detectó un problema en Xen versiones hasta 4.14.x. En la implementación de Ocaml xenstored, la representación interna del árbol tiene casos especiales para el nodo root, porque este nodo no tiene padre. Desafortunadamente, no fueron comprobados los permisos para determinadas operaciones en el nodo root. Los invitados no privilegiados pueden obtener y modificar permisos, enumerar y eliminar el nodo root. (Eliminar todo el árbol de xenstore es una denegación de servicio en todo el host). Lograr el acceso de escritura a xenstore también es posible. Todos los sistemas que usan oxenstored son vulnerables. La construcción y el uso de oxenstored es el valor predeterminado en la distribución Xen previa, si el compilador Ocaml está disponible. Los sistemas que utilizan C xenstored no son vulnerables"
    }
  ],
  "lastModified": "2026-06-17T03:11:19.690",
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