usn-4930-1
Vulnerability from osv_ubuntu
Published
2021-04-29 16:48
Modified
2026-04-22 07:36
Summary
samba vulnerability
Details

Peter Eriksson discovered that Samba incorrectly handled certain negative idmap cache entries. This issue could result in certain users gaining unauthorized access to files, contrary to expected behaviour.

References
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "cves_map": {
          "cves": [
            {
              "id": "CVE-2021-20254",
              "severity": [
                {
                  "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N",
                  "type": "CVSS_V3"
                },
                {
                  "score": "medium",
                  "type": "Ubuntu"
                }
              ]
            }
          ],
          "ecosystem": "Ubuntu:16.04:LTS"
        }
      },
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "ctdb",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "libnss-winbind",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "libpam-winbind",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "libparse-pidl-perl",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "libsmbclient",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "libwbclient0",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "python-samba",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "registry-tools",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "samba",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "samba-common",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "samba-common-bin",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "samba-dsdb-modules",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "samba-libs",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "samba-testsuite",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "samba-vfs-modules",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "smbclient",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          },
          {
            "binary_name": "winbind",
            "binary_version": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "samba",
        "purl": "pkg:deb/ubuntu/samba@2:4.3.11+dfsg-0ubuntu0.16.04.34?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2:4.3.11+dfsg-0ubuntu0.16.04.34"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:4.1.17+dfsg-4ubuntu2",
        "2:4.1.20+dfsg-1ubuntu1",
        "2:4.1.20+dfsg-1ubuntu2",
        "2:4.1.20+dfsg-1ubuntu3",
        "2:4.1.20+dfsg-1ubuntu5",
        "2:4.3.3+dfsg-1ubuntu1",
        "2:4.3.3+dfsg-1ubuntu2",
        "2:4.3.3+dfsg-1ubuntu3",
        "2:4.3.6+dfsg-1ubuntu1",
        "2:4.3.8+dfsg-0ubuntu1",
        "2:4.3.9+dfsg-0ubuntu0.16.04.1",
        "2:4.3.9+dfsg-0ubuntu0.16.04.2",
        "2:4.3.9+dfsg-0ubuntu0.16.04.3",
        "2:4.3.11+dfsg-0ubuntu0.16.04.1",
        "2:4.3.11+dfsg-0ubuntu0.16.04.3",
        "2:4.3.11+dfsg-0ubuntu0.16.04.5",
        "2:4.3.11+dfsg-0ubuntu0.16.04.6",
        "2:4.3.11+dfsg-0ubuntu0.16.04.7",
        "2:4.3.11+dfsg-0ubuntu0.16.04.8",
        "2:4.3.11+dfsg-0ubuntu0.16.04.9",
        "2:4.3.11+dfsg-0ubuntu0.16.04.10",
        "2:4.3.11+dfsg-0ubuntu0.16.04.11",
        "2:4.3.11+dfsg-0ubuntu0.16.04.12",
        "2:4.3.11+dfsg-0ubuntu0.16.04.13",
        "2:4.3.11+dfsg-0ubuntu0.16.04.15",
        "2:4.3.11+dfsg-0ubuntu0.16.04.16",
        "2:4.3.11+dfsg-0ubuntu0.16.04.17",
        "2:4.3.11+dfsg-0ubuntu0.16.04.18",
        "2:4.3.11+dfsg-0ubuntu0.16.04.19",
        "2:4.3.11+dfsg-0ubuntu0.16.04.20",
        "2:4.3.11+dfsg-0ubuntu0.16.04.21",
        "2:4.3.11+dfsg-0ubuntu0.16.04.23",
        "2:4.3.11+dfsg-0ubuntu0.16.04.24",
        "2:4.3.11+dfsg-0ubuntu0.16.04.25",
        "2:4.3.11+dfsg-0ubuntu0.16.04.26",
        "2:4.3.11+dfsg-0ubuntu0.16.04.27",
        "2:4.3.11+dfsg-0ubuntu0.16.04.28",
        "2:4.3.11+dfsg-0ubuntu0.16.04.29",
        "2:4.3.11+dfsg-0ubuntu0.16.04.30",
        "2:4.3.11+dfsg-0ubuntu0.16.04.31",
        "2:4.3.11+dfsg-0ubuntu0.16.04.32"
      ]
    },
    {
      "database_specific": {
        "cves_map": {
          "cves": [
            {
              "id": "CVE-2021-20254",
              "severity": [
                {
                  "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N",
                  "type": "CVSS_V3"
                },
                {
                  "score": "medium",
                  "type": "Ubuntu"
                }
              ]
            }
          ],
          "ecosystem": "Ubuntu:18.04:LTS"
        }
      },
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "ctdb",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "libnss-winbind",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "libpam-winbind",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "libparse-pidl-perl",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "libsmbclient",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "libwbclient0",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "python-samba",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "registry-tools",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "samba",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "samba-common",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "samba-common-bin",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "samba-dsdb-modules",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "samba-libs",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "samba-testsuite",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "samba-vfs-modules",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "smbclient",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          },
          {
            "binary_name": "winbind",
            "binary_version": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "samba",
        "purl": "pkg:deb/ubuntu/samba@2:4.7.6+dfsg~ubuntu-0ubuntu2.23?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2:4.7.6+dfsg~ubuntu-0ubuntu2.23"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:4.6.7+dfsg-1ubuntu3",
        "2:4.7.1+dfsg-1ubuntu1",
        "2:4.7.3+dfsg-1ubuntu1",
        "2:4.7.4+dfsg-1ubuntu1",
        "2:4.7.6+dfsg~ubuntu-0ubuntu1",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.2",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.4",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.5",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.6",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.7",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.9",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.10",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.11",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.13",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.14",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.15",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.16",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.17",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.18",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.19",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.20",
        "2:4.7.6+dfsg~ubuntu-0ubuntu2.21"
      ]
    },
    {
      "database_specific": {
        "cves_map": {
          "cves": [
            {
              "id": "CVE-2021-20254",
              "severity": [
                {
                  "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N",
                  "type": "CVSS_V3"
                },
                {
                  "score": "medium",
                  "type": "Ubuntu"
                }
              ]
            }
          ],
          "ecosystem": "Ubuntu:20.04:LTS"
        }
      },
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "ctdb",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "libnss-winbind",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "libpam-winbind",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "libsmbclient",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "libwbclient0",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "python3-samba",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "registry-tools",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "samba",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "samba-common",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "samba-common-bin",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "samba-dsdb-modules",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "samba-libs",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "samba-testsuite",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "samba-vfs-modules",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "smbclient",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          },
          {
            "binary_name": "winbind",
            "binary_version": "2:4.11.6+dfsg-0ubuntu1.8"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "samba",
        "purl": "pkg:deb/ubuntu/samba@2:4.11.6+dfsg-0ubuntu1.8?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2:4.11.6+dfsg-0ubuntu1.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2:4.10.7+dfsg-0ubuntu2",
        "2:4.10.7+dfsg-0ubuntu3",
        "2:4.11.1+dfsg-3ubuntu1",
        "2:4.11.1+dfsg-3ubuntu2",
        "2:4.11.1+dfsg-3ubuntu4",
        "2:4.11.5+dfsg-1ubuntu1",
        "2:4.11.5+dfsg-1ubuntu2",
        "2:4.11.6+dfsg-0ubuntu1",
        "2:4.11.6+dfsg-0ubuntu1.1",
        "2:4.11.6+dfsg-0ubuntu1.2",
        "2:4.11.6+dfsg-0ubuntu1.3",
        "2:4.11.6+dfsg-0ubuntu1.4",
        "2:4.11.6+dfsg-0ubuntu1.5",
        "2:4.11.6+dfsg-0ubuntu1.6"
      ]
    }
  ],
  "aliases": [],
  "details": "Peter Eriksson discovered that Samba incorrectly handled certain negative\nidmap cache entries. This issue could result in certain users gaining\nunauthorized access to files, contrary to expected behaviour.\n",
  "id": "USN-4930-1",
  "modified": "2026-04-22T07:36:59Z",
  "published": "2021-04-29T16:48:57Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-4930-1"
    },
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2021-20254"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "summary": "samba vulnerability",
  "upstream": [
    "UBUNTU-CVE-2021-20254"
  ]
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.