CVE-2021-20254

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    CVE-2021-20254

    Published: 5 May 2021Last Modified: 8 Jul 2026

    Summary:

    Details: 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: https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EP2VJ73OVBPVSOSTVOMGIEQA3MWF6F7/, https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZAF6L2M6CNAJ2YYYGXPWETTW5YLCWTVT/, https://lists.debian.org/debian-lts-announce/2021/05/msg00023.html, https://security.gentoo.org/glsa/202105-22, https://security.netapp.com/advisory/ntap-20210430-0001/, https://www.samba.org/samba/security/CVE-2021-20254.html, https://bugzilla.redhat.com/show_bug.cgi?id=1949442

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- b1d9ddf738c6e59e489bc9c339ce6de5988b689e
    Fixed -703c6301013f78e80882abfe8375d6a45a176b7f

    Affected versions

    samba-4.13.7
    samba-4.13.6
    samba-4.13.5
    samba-4.13.4
    samba-4.13.3
    samba-4.13.2
    samba-4.13.0

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2021-20254 | CVE-DB