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CVE-2023-4091

19
FAUCET Score

CVE-2023-4091 is a medium-severity vulnerability in Samba, affecting fedoraproject, redhat, and samba products. It allows SMB clients with read-only permissions to truncate files to zero bytes when the "acl_xattr" VFS module is configured with "acl_xattr:ignore system acls = yes". This occurs because the SMB protocol permits implicit file truncation during a read-only open request if an OVERWRITE disposition is also specified, bypassing kernel filesystem permissions. The vulnerability has a CVSS score of 6.5, indicating a network-based attack with low complexity and requiring low privileges, leading to high integrity impact (data loss) but no confidentiality impact. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or inclusion in CISA's KEV catalog, though it has garnered some community discussion and media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.17.12CPE matchmatch criteria
cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
>= 4.18.0, < 4.18.8CPE matchmatch criteria
cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
>= 4.19.0, < 4.19.1CPE matchmatch criteria
cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*
39CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*
3.0CPE matchmatch criteria
cpe:2.3:a:redhat:storage:3.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.17%
Probability of exploitation in next 30 days
EPSS Percentile
64.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0117 is in the 78th percentile among its peer group of 21,977 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (9)

denopatch availablevia llm_extracted
View patch
keraspatch availablevia llm_extracted
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.8 Extended Update SupportFixed in: samba-0:4.17.5-4.el8_8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: samba-0:4.18.6-101.el9_3
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: samba-0:4.18.6-2.el8_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 9.2 Extended Update SupportFixed in: samba-0:4.17.5-104.el9_2
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Virtualization 4 for Red Hat Enterprise Linux 8Fixed in: samba-0:4.15.5-13.el8_6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 9.0 Extended Update SupportFixed in: samba-0:4.15.5-111.el9_0
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.6 Extended Update SupportFixed in: samba-0:4.15.5-13.el8_6
View patch

Vendor Advisories (3)

denollm-deno-650ac71876afb4f8CRITICAL

HP ThinPro 8.1 SP 2 Security Updates

Apr 12, 2024
kerasllm-keras-d13bbd8768a57997CRITICAL

HP ThinPro 8.1 SP 2 Security Updates

Apr 12, 2024
redhatCVE-2023-4091Moderate

samba: SMB clients can truncate files with read-only permissions

Oct 10, 2023

References

lists.debian.org / debian-lts-announce/2024/04/msg00015.html
lists.fedoraproject.org / archives/list/[email protected]/message/ZUMVALLFFDFC53JZMUWA6HPD7HUGAP5I
security.netapp.com / advisory/ntap-20231124-0002
access.redhat.com / errata/RHSA-2023:6209
Third Party Advisory
access.redhat.com / errata/RHSA-2023:6744
Third Party Advisory
access.redhat.com / errata/RHSA-2023:7371
access.redhat.com / errata/RHSA-2023:7408
access.redhat.com / errata/RHSA-2023:7464
access.redhat.com / errata/RHSA-2023:7467
access.redhat.com / security/cve/CVE-2023-4091
Third Party Advisory
bugzilla.redhat.com / show_bug.cgi
Issue Tracking
bugzilla.samba.org / show_bug.cgi
Issue Tracking
samba.org / samba/security/CVE-2023-4091.html
Vendor Advisory