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FKIE_CVE-2021-20254

Vulnerability from fkie_nvd - Published: 2021-05-05 14:15 - Updated: 2026-06-17 03:33
Severity
6.8 (Medium) - CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Summary
A flaw was found in samba. The Samba smbd file server must map Windows group identities (SIDs) into unix group ids (gids). The code that performs this had a flaw that could allow it to read data beyond the end of the array in the case where a negative cache entry had been added to the mapping cache. This could cause the calling code to return those values into the process token that stores the group membership for a user. The highest threat from this vulnerability is to data confidentiality and integrity.
References
secalert@redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=1949442Issue Tracking, Third Party Advisory
secalert@redhat.comhttps://lists.debian.org/debian-lts-announce/2021/05/msg00023.htmlMailing List, Third Party Advisory
secalert@redhat.comhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EP2VJ73OVBPVSOSTVOMGIEQA3MWF6F7/
secalert@redhat.comhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZAF6L2M6CNAJ2YYYGXPWETTW5YLCWTVT/
secalert@redhat.comhttps://security.gentoo.org/glsa/202105-22Third Party Advisory
secalert@redhat.comhttps://security.netapp.com/advisory/ntap-20210430-0001/Third Party Advisory
secalert@redhat.comhttps://www.samba.org/samba/security/CVE-2021-20254.htmlVendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://bugzilla.redhat.com/show_bug.cgi?id=1949442Issue Tracking, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2021/05/msg00023.htmlMailing List, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EP2VJ73OVBPVSOSTVOMGIEQA3MWF6F7/
af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZAF6L2M6CNAJ2YYYGXPWETTW5YLCWTVT/
af854a3a-2127-422b-91ae-364da2661108https://security.gentoo.org/glsa/202105-22Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://security.netapp.com/advisory/ntap-20210430-0001/Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://www.samba.org/samba/security/CVE-2021-20254.htmlVendor Advisory
Impacted products
Vendor Product Version
samba samba *
samba samba *
samba samba *
fedoraproject fedora 32
fedoraproject fedora 33
redhat enterprise_linux 7.0
redhat enterprise_linux 8.0
debian debian_linux 9.0
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "samba",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "samba 4.14.1, samba 4.13.6, samba 4.12.13"
            }
          ]
        }
      ],
      "source": "secalert@redhat.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "B84DE447-47C2-4AFB-867C-20D372058366",
              "versionEndExcluding": "4.12.15",
              "versionStartIncluding": "3.6.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "1B8AF688-C755-4E0A-A80E-D74BF89678D6",
              "versionEndExcluding": "4.13.8",
              "versionStartIncluding": "4.13.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "145DC5A1-4F1B-41BC-8B13-CB270B960BA0",
              "versionEndExcluding": "4.14.4",
              "versionStartIncluding": "4.14.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    },
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*",
              "matchCriteriaId": "36D96259-24BD-44E2-96D9-78CE1D41F956",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*",
              "matchCriteriaId": "E460AA51-FCDA-46B9-AE97-E6676AA5E194",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    },
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*",
              "matchCriteriaId": "142AD0DD-4CF3-4D74-9442-459CE3347E3A",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*",
              "matchCriteriaId": "F4CFF558-3C47-480D-A2F0-BABF26042943",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    },
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*",
              "matchCriteriaId": "DEECE5FC-CACF-4496-A3E7-164736409252",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A flaw was found in samba. The Samba smbd file server must map Windows group identities (SIDs) into unix group ids (gids). The code that performs this had a flaw that could allow it to read data beyond the end of the array in the case where a negative cache entry had been added to the mapping cache. This could cause the calling code to return those values into the process token that stores the group membership for a user. The highest threat from this vulnerability is to data confidentiality and integrity."
    },
    {
      "lang": "es",
      "value": "Se encontr\u00f3 un fallo en samba.\u0026#xa0;El servidor de archivos smbd de Samba debe asignar Windows group identities (SIDs) a unix group ids (gids).\u0026#xa0;El c\u00f3digo que lleva a cabo esto ten\u00eda un fallo que podr\u00eda permitirle leer datos m\u00e1s all\u00e1 del final de la matriz en el caso de que se hubiera agregado una entrada de cach\u00e9 negativa a la cach\u00e9 de mapeo.\u0026#xa0;Esto podr\u00eda causar que el c\u00f3digo de llamada devuelva esos valores al token de proceso que almacena la pertenencia al grupo de un usuario.\u0026#xa0;La mayor amenaza de esta vulnerabilidad es la confidencialidad e integridad de los datos"
    }
  ],
  "id": "CVE-2021-20254",
  "lastModified": "2026-06-17T03:33:33.100",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "MEDIUM",
          "accessVector": "NETWORK",
          "authentication": "SINGLE",
          "availabilityImpact": "NONE",
          "baseScore": 4.9,
          "confidentialityImpact": "PARTIAL",
          "integrityImpact": "PARTIAL",
          "vectorString": "AV:N/AC:M/Au:S/C:P/I:P/A:N",
          "version": "2.0"
        },
        "exploitabilityScore": 6.8,
        "impactScore": 4.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 6.8,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 1.6,
        "impactScore": 5.2,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-05-05T14:15:07.883",
  "references": [
    {
      "source": "secalert@redhat.com",
      "tags": [
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1949442"
    },
    {
      "source": "secalert@redhat.com",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "url": "https://lists.debian.org/debian-lts-announce/2021/05/msg00023.html"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EP2VJ73OVBPVSOSTVOMGIEQA3MWF6F7/"
    },
    {
      "source": "secalert@redhat.com",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZAF6L2M6CNAJ2YYYGXPWETTW5YLCWTVT/"
    },
    {
      "source": "secalert@redhat.com",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://security.gentoo.org/glsa/202105-22"
    },
    {
      "source": "secalert@redhat.com",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://security.netapp.com/advisory/ntap-20210430-0001/"
    },
    {
      "source": "secalert@redhat.com",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://www.samba.org/samba/security/CVE-2021-20254.html"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1949442"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "url": "https://lists.debian.org/debian-lts-announce/2021/05/msg00023.html"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EP2VJ73OVBPVSOSTVOMGIEQA3MWF6F7/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZAF6L2M6CNAJ2YYYGXPWETTW5YLCWTVT/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://security.gentoo.org/glsa/202105-22"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://security.netapp.com/advisory/ntap-20210430-0001/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://www.samba.org/samba/security/CVE-2021-20254.html"
    }
  ],
  "sourceIdentifier": "secalert@redhat.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-125"
        }
      ],
      "source": "secalert@redhat.com",
      "type": "Secondary"
    }
  ]
}



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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

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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