UBUNTU-CVE-2023-4091

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    UBUNTU-CVE-2023-4091

    Published: 10 Oct 2023Last Modified: 22 Apr 2026
    Upstream:
    CVE-2023-4091

    Summary:

    Details: A vulnerability was discovered in Samba, where the flaw allows SMB clients to truncate files, even with read-only permissions when the Samba VFS module "acl_xattr" is configured with "acl_xattr:ignore system acls = yes". The SMB protocol allows opening files when the client requests read-only access but then implicitly truncates the opened file to 0 bytes if the client specifies a separate OVERWRITE create disposition request. The issue arises in configurations that bypass kernel file system permissions checks, relying solely on Samba's permissions.

    References: https://ubuntu.com/security/CVE-2023-4091, https://www.samba.org/samba/security/CVE-2023-4091.html, https://ubuntu.com/security/notices/USN-6425-1, https://ubuntu.com/security/notices/USN-6425-3, https://www.cve.org/CVERecord?id=CVE-2023-4091

    Affected packages

    Package

    Name: samba

    Purl: pkg:deb/ubuntu/samba@2:4.3.11+dfsg-0ubuntu0.14.04.20+esm15?arch=source&distro=esm-infra-legacy/trusty

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -None

    Affected versions

    2:3.6.18-1ubuntu3

    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
    UBUNTU-CVE-2023-4091 | CVE-DB