Samba: smb clients can truncate files with read-only permissions
Priority LOW 34CWE-276Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Partial Red Hat: 22 fixed, 3 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01334 71st percentileScored 2026-11-07
Fix Partial Red Hat: 6 advisoriesRed Hat: 22 fixed, 3 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 8 | — | 4.18.6-2.el8_9 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 8 | — | 4.18.6-2.el8_9 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 8.6 Extended Update Support | — | 4.15.5-13.el8_6 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 8.8 Extended Update Support | — | 4.17.5-4.el8_8 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 9 | — | 4.18.6-101.el9_3 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 9 | — | 4.18.6-101.el9_3 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 9.0 Extended Update Support | — | 4.15.5-111.el9_0 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 9.2 Extended Update Support | — | 4.17.5-104.el9_2 | Patch available | CNA |
| Red Hat | Red Hat Virtualization 4 for Red Hat Enterprise Linux 8 | — | 4.15.5-13.el8_6 | Patch available | CNA |
| Red Hat | Red Hat Enterprise Linux 6 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Enterprise Linux 6 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Enterprise Linux 7 | — | — | No fix listed | CNA |
| Red Hat | Red Hat Storage 3 | — | — | No fix listed | CNA |
- Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in 4.18.6-2.el8_9 Patch available CNA
- Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in 4.18.6-2.el8_9 Patch available CNA
- Red Hat Enterprise Linux 8.6 Extended Update Support VendorRed Hat Affected — Fixed in 4.15.5-13.el8_6 Patch available CNA
- Red Hat Enterprise Linux 8.8 Extended Update Support VendorRed Hat Affected — Fixed in 4.17.5-4.el8_8 Patch available CNA
- Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in 4.18.6-101.el9_3 Patch available CNA
- Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in 4.18.6-101.el9_3 Patch available CNA
- Red Hat Enterprise Linux 9.0 Extended Update Support VendorRed Hat Affected — Fixed in 4.15.5-111.el9_0 Patch available CNA
- Red Hat Enterprise Linux 9.2 Extended Update Support VendorRed Hat Affected — Fixed in 4.17.5-104.el9_2 Patch available CNA
- Red Hat Virtualization 4 for Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in 4.15.5-13.el8_6 Patch available CNA
- Red Hat Enterprise Linux 6 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Enterprise Linux 6 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Enterprise Linux 7 VendorRed Hat Affected — Fixed in — No fix listed CNA
- Red Hat Storage 3 VendorRed Hat Affected — Fixed in — No fix listed CNA
CPE configurations NVD · 5
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:* | before 4.17.12; 4.18.0 to before 4.18.8; 4.19.0 to before 4.19.1 | Vulnerable | Samba |
| cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:* | 39 | Vulnerable | Fedoraproject |
| cpe:2.3:a:redhat:storage:3.0:*:*:*:*:*:*:* | 3.0 | Vulnerable | Red Hat |
| cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* | 8.0 | Vulnerable | Red Hat |
| cpe:2.3:o:redhat:enterprise_linux_eus:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Red Hat |
- cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:* Versions before 4.17.12; 4.18.0 to before 4.18.8; 4.19.0 to before 4.19.1 Vulnerable ·Samba
- cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:* Versions 39 Vulnerable ·Fedoraproject
- cpe:2.3:a:redhat:storage:3.0:*:*:*:*:*:*:* Versions 3.0 Vulnerable ·Red Hat
- cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* Versions 8.0 Vulnerable ·Red Hat
- cpe:2.3:o:redhat:enterprise_linux_eus:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Red Hat
Remediation
Red Hat 6 advisories
- RHSA-2023:7467 Released 2023-11-22 · Red Hat rating Moderatesamba security update
- Red Hat CodeReady Linux Builder (v. 8) libnetapi-devel-4.18.6-2.el8_9, libsmbclient-devel-4.18.6-2.el8_9, libwbclient-devel-4.18.6-2.el8_9 +2
- Red Hat Enterprise Linux AppStream (v. 8) samba-vfs-iouring-4.18.6-2.el8_9
- Red Hat Enterprise Linux BaseOS (v. 8) ctdb-4.18.6-2.el8_9, libnetapi-4.18.6-2.el8_9, libsmbclient-4.18.6-2.el8_9 +25
- RHSA-2023:7464 Released 2023-11-22 · Red Hat rating Moderatesamba security update
- Red Hat CodeReady Linux Builder EUS (v.8.8) libnetapi-devel-4.17.5-4.el8_8, libsmbclient-devel-4.17.5-4.el8_8, libwbclient-devel-4.17.5-4.el8_8 +2
- Red Hat Enterprise Linux AppStream EUS (v.8.8) samba-vfs-iouring-4.17.5-4.el8_8
- Red Hat Enterprise Linux BaseOS EUS (v.8.8) ctdb-4.17.5-4.el8_8, libnetapi-4.17.5-4.el8_8, libsmbclient-4.17.5-4.el8_8 +25
- RHSA-2023:7408 Released 2023-11-21 · Red Hat rating Moderatesamba security update
- Red Hat CodeReady Linux Builder EUS (v.8.6) libsmbclient-devel-4.15.5-13.el8_6, libwbclient-devel-4.15.5-13.el8_6, samba-devel-4.15.5-13.el8_6
- Red Hat Enterprise Linux AppStream EUS (v.8.6) samba-vfs-iouring-4.15.5-13.el8_6
- Red Hat Enterprise Linux BaseOS EUS (v.8.6) ctdb-4.15.5-13.el8_6, libsmbclient-4.15.5-13.el8_6, libwbclient-4.15.5-13.el8_6 +18
- Red Hat Virtualization 4 Hypervisor for RHEL 8 libsmbclient-4.15.5-13.el8_6, libwbclient-4.15.5-13.el8_6, samba-4.15.5-13.el8_6 +3
Show 3 more Red Hat advisories
- RHSA-2023:7371 Released 2023-11-21 · Red Hat rating Moderatesamba security update
- Red Hat CodeReady Linux Builder EUS (v.9.2) libnetapi-devel-4.17.5-104.el9_2, libsmbclient-devel-4.17.5-104.el9_2, libwbclient-devel-4.17.5-104.el9_2 +6
- Red Hat Enterprise Linux AppStream EUS (v.9.2) samba-client-4.17.5-104.el9_2, samba-krb5-printing-4.17.5-104.el9_2, samba-vfs-iouring-4.17.5-104.el9_2 +3
- Red Hat Enterprise Linux BaseOS EUS (v.9.2) libnetapi-4.17.5-104.el9_2, libsmbclient-4.17.5-104.el9_2, libwbclient-4.17.5-104.el9_2 +15
- Red Hat Enterprise Linux Resilient Storage EUS (v.9.2) ctdb-4.17.5-104.el9_2
- RHSA-2023:6744 Released 2023-11-07 · Red Hat rating Moderatesamba security update
- Red Hat CodeReady Linux Builder (v. 9) libnetapi-devel-4.18.6-101.el9_3, libsmbclient-devel-4.18.6-101.el9_3, libwbclient-devel-4.18.6-101.el9_3 +6
- Red Hat Enterprise Linux AppStream (v. 9) samba-client-4.18.6-101.el9_3, samba-krb5-printing-4.18.6-101.el9_3, samba-vfs-iouring-4.18.6-101.el9_3 +3
- Red Hat Enterprise Linux BaseOS (v. 9) libnetapi-4.18.6-101.el9_3, libsmbclient-4.18.6-101.el9_3, libwbclient-4.18.6-101.el9_3 +15
- Red Hat Enterprise Linux Resilient Storage (v. 9) ctdb-4.18.6-101.el9_3
- RHSA-2023:6209 Released 2023-10-31 · Red Hat rating Moderatesamba security update
- Red Hat CodeReady Linux Builder EUS (v.9.0) libsmbclient-devel-4.15.5-111.el9_0, libwbclient-devel-4.15.5-111.el9_0, samba-devel-4.15.5-111.el9_0 +3
- Red Hat Enterprise Linux AppStream EUS (v.9.0) samba-client-4.15.5-111.el9_0, samba-krb5-printing-4.15.5-111.el9_0, samba-vfs-iouring-4.15.5-111.el9_0 +3
- Red Hat Enterprise Linux BaseOS EUS (v.9.0) libsmbclient-4.15.5-111.el9_0, libwbclient-4.15.5-111.el9_0, python3-samba-4.15.5-111.el9_0 +8
- Red Hat Enterprise Linux Resilient Storage EUS (v.9.0) ctdb-4.15.5-111.el9_0
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 and 8 more products — RHSA-2023:6209
3 records Highest priority Priority MEDIUM 1 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2023-03679 Samba: smbd allows client access to unix domain sockets on the file system as rootPriority MEDIUM 47
- TI-2023-22772 Samba: "rpcecho" development server allows denial of service via sleep() call on ad dcPriority LOW 33
- Advisory ·
Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 and 8 more products — RHSA-2023:6744
3 records Highest priority Priority MEDIUM 1 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2023-03679 Samba: smbd allows client access to unix domain sockets on the file system as rootPriority MEDIUM 47
- TI-2023-22772 Samba: "rpcecho" development server allows denial of service via sleep() call on ad dcPriority LOW 33
Show 4 more groups
- Advisory ·
Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 and 8 more products — RHSA-2023:7371
3 records Highest priority Priority MEDIUM 1 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2023-03679 Samba: smbd allows client access to unix domain sockets on the file system as rootPriority MEDIUM 47
- TI-2023-22772 Samba: "rpcecho" development server allows denial of service via sleep() call on ad dcPriority LOW 33
- Advisory ·
Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 and 8 more products — RHSA-2023:7408
3 records Highest priority Priority MEDIUM 1 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2023-03679 Samba: smbd allows client access to unix domain sockets on the file system as rootPriority MEDIUM 47
- TI-2023-22772 Samba: "rpcecho" development server allows denial of service via sleep() call on ad dcPriority LOW 33
- Advisory ·
Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 and 8 more products — RHSA-2023:7464
3 records Highest priority Priority MEDIUM 1 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2023-03679 Samba: smbd allows client access to unix domain sockets on the file system as rootPriority MEDIUM 47
- TI-2023-22772 Samba: "rpcecho" development server allows denial of service via sleep() call on ad dcPriority LOW 33
- Advisory ·
Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 and 8 more products — RHSA-2023:7467
3 records Highest priority Priority MEDIUM 1 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2023-03679 Samba: smbd allows client access to unix domain sockets on the file system as rootPriority MEDIUM 47
- TI-2023-22772 Samba: "rpcecho" development server allows denial of service via sleep() call on ad dcPriority LOW 33
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat Storage 3 | Affected | No fix planned: Out of support scope |
| Red Hat CodeReady Linux Builder (v. 8) | Fixed | RHSA-2023:7467 |
| Red Hat CodeReady Linux Builder (v. 9) | Fixed | RHSA-2023:6744 |
| Red Hat CodeReady Linux Builder EUS (v.8.6) | Fixed | RHSA-2023:7408 |
| Red Hat CodeReady Linux Builder EUS (v.8.8) | Fixed | RHSA-2023:7464 |
| Red Hat CodeReady Linux Builder EUS (v.9.0) | Fixed | RHSA-2023:6209 |
| Red Hat CodeReady Linux Builder EUS (v.9.2) | Fixed | RHSA-2023:7371 |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2023:7467 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2023:6744 |
| Red Hat Enterprise Linux AppStream EUS (v.8.6) | Fixed | RHSA-2023:7408 |
| Red Hat Enterprise Linux AppStream EUS (v.8.8) | Fixed | RHSA-2023:7464 |
| Red Hat Enterprise Linux AppStream EUS (v.9.0) | Fixed | RHSA-2023:6209 |
| Red Hat Enterprise Linux AppStream EUS (v.9.2) | Fixed | RHSA-2023:7371 |
| Red Hat Enterprise Linux BaseOS (v. 8) | Fixed | RHSA-2023:7467 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2023:6744 |
| Red Hat Enterprise Linux BaseOS EUS (v.8.6) | Fixed | RHSA-2023:7408 |
| Red Hat Enterprise Linux BaseOS EUS (v.8.8) | Fixed | RHSA-2023:7464 |
| Red Hat Enterprise Linux BaseOS EUS (v.9.0) | Fixed | RHSA-2023:6209 |
| Red Hat Enterprise Linux BaseOS EUS (v.9.2) | Fixed | RHSA-2023:7371 |
| Red Hat Enterprise Linux Resilient Storage (v. 9) | Fixed | RHSA-2023:6744 |
| Red Hat Enterprise Linux Resilient Storage EUS (v.9.0) | Fixed | RHSA-2023:6209 |
| Red Hat Enterprise Linux Resilient Storage EUS (v.9.2) | Fixed | RHSA-2023:7371 |
| Red Hat Virtualization 4 Hypervisor for RHEL 8 | Fixed | RHSA-2023:7408 |
Timeline
- 2026-10-02 Threatist record created from CVE-2023-4091
- 2026-10-03 Alias added: GHSA-f6jj-3gjw-frjm
References
More Red Hat Enterprise Linux vulnerabilities
- TI-2019-08259 Underflow in PHP-FPM can lead to RCE KEVCVSS 3.1CRITICAL 9.8
- TI-2018-10530 Code injection in [UNKNOWN] RichFaces KEVCVSS 3.1CRITICAL 9.8
- TI-2014-05975 GNU Bash through 4.3 bash43-025 processes trailing strings after certain malformed… KEVCVSS 3.1CRITICAL 9.8
- TI-2014-05157 GNU Bash through 4.3 processes trailing strings after function definitions in the values… KEVCVSS 3.1CRITICAL 9.8
- TI-2025-23530 Sudo before 1.9.17p1 allows local users to obtain root access because /etc/nsswitch.conf… KEVCVSS 3.1CRITICAL 9.3
- TI-2021-17490 mod_proxy SSRF KEVCVSS 3.1CRITICAL 9.0
Sources
- CVE-2023-4091 · CVE Program
- CVE-2023-4091 · NVD
- FIRST EPSS
- GHSA-f6jj-3gjw-frjm · GitHub Advisory Database · CC BY 4.0
- CVE-2023-4091 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences