CVE-2023-4091
Samba: smb clients can truncate files with read-only permissions
- Published
- Updated
- Reserved
- Assigned by
- redhat
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| redhatCNA (assigner) | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N |
| NVDNVD · Modified | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 1.3% · top 29% of all CVEs (5 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.
Weakness
Affected products
Red Hat · Red Hat Enterprise Linux 8
- unaffected 0:4.18.6-2.el8_9 – < *
Red Hat · Red Hat Enterprise Linux 8
- unaffected 0:4.18.6-2.el8_9 – < *
Red Hat · Red Hat Enterprise Linux 8.6 Extended Update Support
- unaffected 0:4.15.5-13.el8_6 – < *
Red Hat · Red Hat Enterprise Linux 8.8 Extended Update Support
- unaffected 0:4.17.5-4.el8_8 – < *
Red Hat · Red Hat Enterprise Linux 9
- unaffected 0:4.18.6-101.el9_3 – < *
Red Hat · Red Hat Enterprise Linux 9
- unaffected 0:4.18.6-101.el9_3 – < *
Red Hat · Red Hat Enterprise Linux 9.0 Extended Update Support
- unaffected 0:4.15.5-111.el9_0 – < *
Red Hat · Red Hat Enterprise Linux 9.2 Extended Update Support
- unaffected 0:4.17.5-104.el9_2 – < *
Red Hat · Red Hat Virtualization 4 for Red Hat Enterprise Linux 8
- unaffected 0:4.15.5-13.el8_6 – < *
Red Hat · Red Hat Enterprise Linux 6
All versions: unknown
Red Hat · Red Hat Enterprise Linux 6
All versions: unknown
Red Hat · Red Hat Enterprise Linux 7
All versions: unknown
All versions: unknown
What to do
Workaround: The vulnerability is most commonly associated with the "acl_xattr" module and can be mitigated by setting: ~~~ "acl_xattr:ignore system acls = no" ~~~
References (13)
- RHSA-2023:6209 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2023:6744 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2023:7371 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2023:7408 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2023:7464 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2023:7467 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- https://access.redhat.com/security/cve/CVE-2023-4091 (opens in a new tab)vdb-entryx_refsource_REDHATx_transferred
- RHBZ#2241882 (opens in a new tab)issue-trackingx_refsource_REDHATx_transferred
- https://bugzilla.samba.org/show_bug.cgi?id=15439 (opens in a new tab)x_transferred
- https://www.samba.org/samba/security/CVE-2023-4091.html (opens in a new tab)x_transferred
- https://lists.debian.org/debian-lts-announce/2024/04/msg00015.html (opens in a new tab)x_transferred
- https://lists.fedoraproject.org/archives/list/[email protected]/message/ZUMVALLFFDFC53JZMUWA6HPD7HUGAP5I/ (opens in a new tab)x_transferred
- https://security.netapp.com/advisory/ntap-20231124-0002/ (opens in a new tab)x_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2023-4091)Record last updated .