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.

How to fix CVE-2023-4091

To remediate CVE-2023-4091, upgrade the affected package to a fixed version below.

• —upgrade to 4.18.8-r0 or later
• —upgrade to 2:4.13.13+dfsg-1~deb11u6 or later

Is CVE-2023-4091 being exploited?

Low — EPSS is 0.4%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 4.18.8-r0
• from 0, < 2:4.13.13+dfsg-1~deb11u6

CVSS scores

References (2)

• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2023-4091
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2023-4091