CVE-2026-109411

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    CVE-2026-109411

    Published: 28 Oct 2026Last Modified: 5 Nov 2026

    Summary: Samba: access control bypass via vfs_ceph_rgw case-insensitive open

    Details: An access control bypass flaw was identified in Samba's vfs_ceph_rgw module in it's openat() function. An authenticated user can bypass access controls to read or overwrite restricted files on shares configured with the experimental vfs_ceph_rgw module. When a client requests an existing file using mismatched character casing, the module fails to perform a case-insensitive lookup correctly, causing the server to treat the operation as creating a new file. As a result, the server skips standard permission checks on the existing file, allowing the attacker to access or overwrite sensitive data owned by other users.

    References: https://access.redhat.com/downloads/content/package-browser/, https://attachments.samba.org/attachment.cgi?id=19294, https://attachments.samba.org/attachment.cgi?id=19295, https://access.redhat.com/security/cve/CVE-2026-109411, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/109xxx/CVE-2026-109411.json, https://nvd.nist.gov/vuln/detail/CVE-2026-109411, https://bugzilla.redhat.com/show_bug.cgi?id=2552136, https://bugzilla.samba.org/show_bug.cgi?id=16276, https://gitlab.com/samba-team/samba

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- b439e3ec13425de85e03eb4ac394ad15273decf7
    Fixed -02e8e3f93f4af787bcb3389cbff9e22e74567eb2

    Affected versions

    samba-4.25.0

    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-2026-109411 | CVE-DB