« Volver al listado

CVE-2020-16120

Estado: ModificadaMedia (4.4)—

Overlayfs did not properly perform permission checking when copying up files in an overlayfs and could be exploited from within a user namespace, if, for example, unprivileged user namespaces were allowed. It was possible to have a file not readable by an unprivileged user to be copied to a mountpoint controlled by the user, like a removable device. This was introduced in kernel version 4.19 by commit d1d04ef ("ovl: stack file ops").

Leer descripción completaMostrar menos

This was fixed in kernel version 5.8 by commits 56230d9 ("ovl: verify permissions in ovl_path_open()"), 48bd024 ("ovl: switch to mounter creds in readdir") and 05acefb ("ovl: check permission to open real file"). Additionally, commits 130fdbc ("ovl: pass correct flags for opening real directory") and 292f902 ("ovl: call secutiry hook in ovl_real_ioctl()") in kernel 5.8 might also be desired or necessary. These additional commits introduced a regression in overlay mounts within user namespaces which prevented access to files with ownership outside of the user namespace. This regression was mitigated by subsequent commit b6650da ("ovl: do not fail because of O_NOATIMEi") in kernel 5.11.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (2)

Canonical — Ubuntu LinuxLinux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2020-16120",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 2.1,
          "accessVector": "LOCAL",
          "vectorString": "AV:L/AC:L/Au:N/C:P/I:N/A:N",
          "authentication": "NONE",
          "integrityImpact": "NONE",
          "accessComplexity": "LOW",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "PARTIAL"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "LOW",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 3.9,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security@ubuntu.com",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.1,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "HIGH",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.4
      },
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 4.4,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "HIGH",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 0.8
      }
    ]
  },
  "affected": [
    {
      "source": "security@ubuntu.com",
      "affectedData": [
        {
          "vendor": "Linux kernel",
          "product": "Linux kernel",
          "versions": [
            {
              "status": "affected",
              "version": "5.11-stable",
              "lessThan": "5.11.0",
              "versionType": "custom"
            }
          ]
        }
      ]
    }
  ],
  "published": "2021-02-10T20:15:15.150",
  "references": [
    {
      "url": "https://git.kernel.org/linus/05acefb4872dae89e772729efb194af754c877e8",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "security@ubuntu.com"
    },
    {
      "url": "https://git.kernel.org/linus/48bd024b8a40d73ad6b086de2615738da0c7004f",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "security@ubuntu.com"
    },
    {
      "url": "https://git.kernel.org/linus/56230d956739b9cb1cbde439d76227d77979a04d",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "security@ubuntu.com"
    },
    {
      "url": "https://git.kernel.org/linus/b6650dab404c701d7fe08a108b746542a934da84",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "security@ubuntu.com"
    },
    {
      "url": "https://git.kernel.org/linus/d1d04ef8572bc8c22265057bd3d5a79f223f8f52",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "security@ubuntu.com"
    },
    {
      "url": "https://launchpad.net/bugs/1894980",
      "tags": [
        "Issue Tracking",
        "Patch",
        "Third Party Advisory"
      ],
      "source": "security@ubuntu.com"
    },
    {
      "url": "https://launchpad.net/bugs/1900141",
      "tags": [
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "source": "security@ubuntu.com"
    },
    {
      "url": "https://ubuntu.com/USN-4576-1",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "security@ubuntu.com"
    },
    {
      "url": "https://ubuntu.com/USN-4577-1",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "security@ubuntu.com"
    },
    {
      "url": "https://ubuntu.com/USN-4578-1",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "security@ubuntu.com"
    },
    {
      "url": "https://www.openwall.com/lists/oss-security/2020/10/14/2",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "security@ubuntu.com"
    },
    {
      "url": "https://git.kernel.org/linus/05acefb4872dae89e772729efb194af754c877e8",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://git.kernel.org/linus/48bd024b8a40d73ad6b086de2615738da0c7004f",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://git.kernel.org/linus/56230d956739b9cb1cbde439d76227d77979a04d",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://git.kernel.org/linus/b6650dab404c701d7fe08a108b746542a934da84",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://git.kernel.org/linus/d1d04ef8572bc8c22265057bd3d5a79f223f8f52",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://launchpad.net/bugs/1894980",
      "tags": [
        "Issue Tracking",
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://launchpad.net/bugs/1900141",
      "tags": [
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://ubuntu.com/USN-4576-1",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://ubuntu.com/USN-4577-1",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://ubuntu.com/USN-4578-1",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://www.openwall.com/lists/oss-security/2020/10/14/2",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security@ubuntu.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-266"
        }
      ]
    },
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-Other"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Overlayfs did not properly perform permission checking when copying up files in an overlayfs and could be exploited from within a user namespace, if, for example, unprivileged user namespaces were allowed. It was possible to have a file not readable by an unprivileged user to be copied to a mountpoint controlled by the user, like a removable device. This was introduced in kernel version 4.19 by commit d1d04ef (\"ovl: stack file ops\"). This was fixed in kernel version 5.8 by commits 56230d9 (\"ovl: verify permissions in ovl_path_open()\"), 48bd024 (\"ovl: switch to mounter creds in readdir\") and 05acefb (\"ovl: check permission to open real file\"). Additionally, commits 130fdbc (\"ovl: pass correct flags for opening real directory\") and 292f902 (\"ovl: call secutiry hook in ovl_real_ioctl()\") in kernel 5.8 might also be desired or necessary. These additional commits introduced a regression in overlay mounts within user namespaces which prevented access to files with ownership outside of the user namespace. This regression was mitigated by subsequent commit b6650da (\"ovl: do not fail because of O_NOATIMEi\") in kernel 5.11."
    },
    {
      "lang": "es",
      "value": "Overlayfs no realizaba apropiadamente la comprobación de permisos al copiar archivos en un overlayfs y podría explotarse desde dentro de un espacio de nombre de usuario, si, por ejemplo, se permitieran espacios de nombre de usuario sin privilegios. Era posible tener un archivo no legible por un usuario sin privilegios para ser copiado en un punto de montaje controlado por el usuario, como un dispositivo extraíble. Esto fue introducido en la versión 4.19 del kernel mediante la commit d1d04ef (\"ovl: stack file ops\"). Esto se corrigió en la versión 5.8 del kernel mediante las commits 56230d9 (\"ovl: verify permissions in ovl_path_open()\"), 48bd024 (\"ovl: switch to mounter creds in readdir\" y 05acefb (\"ovl: check permission to open real file\") . Además, confirma 130fdbc (\"ovl: pass correct flags for opening real directory\") y 292f902 (\"ovl: call secutiry hook in ovl_real_ioctl()\") en el kernel 5.8 también podría ser deseable o necesario. Estas commits adicionales introdujeron una regresión en los montajes de superposición dentro de los espacios de nombres de usuarios que impidieron el acceso a archivos con propiedad fuera del espacio de nombres de usuarios. Esta regresión fue mitigada por la subsiguiente Commit b6650da (\"ovl: do not fail because of O_NOATIMEi\") en el kernel versión 5.11"
    }
  ],
  "lastModified": "2026-06-17T02:57:44.547",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "89EC14A5-9B15-472C-A870-D93968B329AD",
              "versionEndExcluding": "5.11"
            }
          ],
          "operator": "OR"
        }
      ]
    },
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "815D70A8-47D3-459C-A32C-9FEACA0659D1"
            },
            {
              "criteria": "cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "F7016A2A-8365-4F1A-89A2-7A19F2BCAE5B"
            },
            {
              "criteria": "cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "23A7C53F-B80F-4E6A-AFA9-58EEA84BE11D"
            },
            {
              "criteria": "cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "902B8056-9E37-443B-8905-8AA93E2447FB"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "security@ubuntu.com"
}