CVE-2023-4091 MEDIUM

CVE-2023-4091: Samba: smb clients can truncate files with read-only permissions

Vendor Red Hat
Product Red Hat Enterprise Linux 6
Weakness CWE-276
Published November 3, 2023
Last update November 20, 2025

CVSS base score

6.5/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality None
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

November 3, 2023 CVE published
November 20, 2025 Record updated