Vulnerability in Samba
CVE-2023-4091
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.013 (70.7th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 71st percentile — 70.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.012 · newest: 0.013 · change: +0.001
Affected products
- Samba
- Fedoraproject Fedora — versions 39
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8 — versions 0:4.18.6-2.el8_9
- Red Hat Enterprise Linux 8.6 Extended Update Support — versions 0:4.15.5-13.el8_6
- Red Hat Enterprise Linux 8.8 Extended Update Support — versions 0:4.17.5-4.el8_8
- Red Hat Enterprise Linux 9 — versions 0:4.18.6-101.el9_3
- Red Hat Enterprise Linux 9.0 Extended Update Support — versions 0:4.15.5-111.el9_0
- Red Hat Enterprise Linux 9.2 Extended Update Support — versions 0:4.17.5-104.el9_2
Weakness classification (CWE)
Public proof-of-concept exploits
References
- access.redhat.com/errata/RHSA-2023:6209 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2023:6744 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2023:7371 (vendor-advisory)
- access.redhat.com/errata/RHSA-2023:7408 (vendor-advisory)
- access.redhat.com/errata/RHSA-2023:7464 (vendor-advisory)
- access.redhat.com/errata/RHSA-2023:7467 (vendor-advisory)
- access.redhat.com/security/cve/CVE-2023-4091 (Third Party Advisory, vdb-entry)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking, Issue Tracking)
- bugzilla.samba.org/show_bug.cgi (Issue Tracking)
- www.samba.org/samba/security/CVE-2023-4091.html (Vendor Advisory)
Frequently asked questions
- What is CVE-2023-4091?
- CVE-2023-4091 is a medium-severity vulnerability in Samba, classified under Incorrect Default Permissions. CVSS score: 6.5/10. Published 2023-11-03.
- How severe is CVE-2023-4091?
- Medium severity. CVSS v3 base score is 6.5 out of 10.
- Is CVE-2023-4091 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.