6.5

CVE-2023-4091: Samba: smb clients can truncate files with read-only permissions

Modified
AliasesALPINE-CVE-2023-4091SUSE-SU-2023:4040-1UBUNTU-CVE-2023-4091
Published 03-11-2023Last modified 20-11-2025

Vulnerability summary

CVE-2023-4091 is a medium (CVSS 6.5) Incorrect Default Permissions vulnerability in fedoraproject fedora. EPSS estimates a 1.33% chance of exploitation in the next 30 days, higher than 71.2% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 6.5, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)
EPSS score
1.33%
0%100%
Low · +0.15 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 15 · Related 6
DLA-3792-1DSA-5525-1DSA-5647-1MGASA-2023-0340OPENSUSE-SU-2024:13332-1RHSA-2023:6209

Timeline

  1. 03-11-2023
    PublishedVulnerability first disclosed.
  2. 20-11-2025
    Last modifiedVulnerability information updated.

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

5 scores · 5 sources · 1 version

EPSS trend

Probability

1.33%

Chance of exploitation in the next 30 days

Percentile

71%

Versus all other CVEs

30-day change

Increase +0.15 pp

From 1.18% on 05-10-2026

05-10-202604-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Suse4 products
  • samba&distro=SUSE Linux Enterprise High Availability Extension 12 SP5< 4.15.13+git.625.ac658f2f12-3.88.1
  • samba&distro=SUSE Linux Enterprise Server 12 SP5< 4.15.13+git.625.ac658f2f12-3.88.1
  • samba&distro=SUSE Linux Enterprise Server for SAP Applications 12 SP5< 4.15.13+git.625.ac658f2f12-3.88.1
  • samba&distro=SUSE Linux Enterprise Software Development Kit 12 SP5< 4.15.13+git.625.ac658f2f12-3.88.1
Redhat3 products
Alpine1 product
  • samba≥ 4.18.0, < 4.18.8-r0
Debian1 product
  • samba< 2:4.17.12+dfsg-0+deb12u1 | < 2:4.19.1+dfsg-1
Fedoraproject1 product
Samba1 product
  • samba< 4.17.12 | ≥ 4.18.0, < 4.18.8 | ≥ 4.19.0, < 4.19.1
Ubuntu1 product
  • sambaAll versions (No fix recorded) | < 2:4.15.13+dfsg-0ubuntu0.20.04.6 | < 2:4.15.13+dfsg-0ubuntu1.5 | < 2:4.18.6+dfsg-1ubuntu2.1

7 vendors · 12 products

References

22 links
Show all 22 references