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CVE-2021-20254

Estado: ModificadaMedia (6.8)—

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.

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 (4)

Debian — Debian LinuxFedoraproject — FedoraRedhat — Enterprise LinuxSamba — Samba

CWE

Referencias

JSON original (NVD)

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  "id": "CVE-2021-20254",
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          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:M/Au:S/C:P/I:P/A:N",
          "authentication": "SINGLE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "MEDIUM",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "PARTIAL"
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      "source": "secalert@redhat.com",
      "description": [
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          "value": "CWE-125"
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    {
      "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 encontró un fallo en samba. El servidor de archivos smbd de Samba debe asignar Windows group identities (SIDs) a unix group ids (gids). El código que lleva a cabo esto tenía un fallo que podría permitirle leer datos más allá del final de la matriz en el caso de que se hubiera agregado una entrada de caché negativa a la caché de mapeo. Esto podría causar que el código de llamada devuelva esos valores al token de proceso que almacena la pertenencia al grupo de un usuario. La mayor amenaza de esta vulnerabilidad es la confidencialidad e integridad de los datos"
    }
  ],
  "lastModified": "2026-06-17T03:33:33.100",
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