UBUNTU-CVE-2023-4091

Description

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.

CVSS Metrics

• v3.1•MEDIUM•Score: 6.5CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Affected Systems

• ubuntu•samba

  all | < 2:4.15.13+dfsg-0ubuntu0.20.04.6 | < 2:4.15.13+dfsg-0ubuntu1.5 | < 2:4.18.6+dfsg-1ubuntu2.1

References (5)

• 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