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.
access.redhat.com/errata/RHSA-2023:6209
access.redhat.com/errata/RHSA-2023:6744
access.redhat.com/errata/RHSA-2023:7371
access.redhat.com/errata/RHSA-2023:7408
access.redhat.com/errata/RHSA-2023:7464
access.redhat.com/errata/RHSA-2023:7467
access.redhat.com/security/cve/CVE-2023-4091
bugzilla.redhat.com/show_bug.cgi?id=2241882
bugzilla.samba.org/show_bug.cgi?id=15439
lists.fedoraproject.org/archives/list/[email protected]/message/ZUMVALLFFDFC53JZMUWA6HPD7HUGAP5I/
security.netapp.com/advisory/ntap-20231124-0002/
www.samba.org/samba/security/CVE-2023-4091.html