CVE-2023-4091
Samba: smb clients can truncate files with read-only permissions
CVSS Score
6.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-276 |
| Vendor | red hat |
| Product | red hat enterprise linux 8 |
| Published | Nov 3, 2023 |
| Last Updated | Nov 20, 2025 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Affected Versions
Red Hat / Red Hat Enterprise Linux 8
All versions affected Red Hat / Red Hat Enterprise Linux 8
All versions affected Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support
All versions affected Red Hat / Red Hat Enterprise Linux 8.8 Extended Update Support
All versions affected Red Hat / Red Hat Enterprise Linux 9
All versions affected Red Hat / Red Hat Enterprise Linux 9
All versions affected Red Hat / Red Hat Enterprise Linux 9.0 Extended Update Support
All versions affected Red Hat / Red Hat Enterprise Linux 9.2 Extended Update Support
All versions affected Red Hat / Red Hat Virtualization 4 for Red Hat Enterprise Linux 8
All versions affected Red Hat / Red Hat Enterprise Linux 6
All versions affected Red Hat / Red Hat Enterprise Linux 6
All versions affected Red Hat / Red Hat Enterprise Linux 7
All versions affected Red Hat / Red Hat Storage 3
All versions affected References
access.redhat.com: https://access.redhat.com/errata/RHSA-2023:6209 access.redhat.com: https://access.redhat.com/errata/RHSA-2023:6744 access.redhat.com: https://access.redhat.com/errata/RHSA-2023:7371 access.redhat.com: https://access.redhat.com/errata/RHSA-2023:7408 access.redhat.com: https://access.redhat.com/errata/RHSA-2023:7464 access.redhat.com: https://access.redhat.com/errata/RHSA-2023:7467 access.redhat.com: https://access.redhat.com/security/cve/CVE-2023-4091 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2241882 bugzilla.samba.org: https://bugzilla.samba.org/show_bug.cgi?id=15439 samba.org: https://www.samba.org/samba/security/CVE-2023-4091.html lists.debian.org: https://lists.debian.org/debian-lts-announce/2024/04/msg00015.html lists.fedoraproject.org: https://lists.fedoraproject.org/archives/list/[email protected]/message/ZUMVALLFFDFC53JZMUWA6HPD7HUGAP5I/ security.netapp.com: https://security.netapp.com/advisory/ntap-20231124-0002/