CVE-2023-4091
Samba: smb clients can truncate files with read-only permissions
No known exploitation. EPSS puts it in the 66th percentile. A vendor fix is available.
What to do
The vendor has published a fix. Version details are below where the sources state them.
What it is
From the CVE record
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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
1.2% chance of exploitation activity in the next 30 days, which ranks it in the 66th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
7 events over 965 days, from the signal feeds we watch.
- OpenVAS check added
- Patch availableworkaround available, record updated
- Publishedweakness classified, att&ck mapped
Affected products
- Red Hat Enterprise Linux 8Operating Systems / linux-distro
- Red Hat Enterprise Linux 8.6 Extended Update SupportOperating Systems / linux-distro
- Red Hat Enterprise Linux 8.8 Extended Update SupportOperating Systems / linux-distro
- Red Hat Enterprise Linux 9.0 Extended Update SupportOperating Systems / linux-distro
- Red Hat Enterprise Linux 9.2 Extended Update SupportOperating Systems / linux-distro
- Red Hat Virtualization 4 for Red Hat Enterprise Linux 8Operating Systems / linux-distro
- Red Hat Storage 3Databases / data-warehouse-analytics
- storageOperating Systems / linux-distro
And 10 more affected products. See all after sign-in
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Scored 6.5 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required LowRequires basic user-level privileges
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality NoneNo confidentiality impact
- Integrity HighTotal loss of integrity — attacker can modify any data in the component
- Availability NoneNo availability impact
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
- Privilege EscalationT1068Exploitation for Privilege Escalationmedium confidence
Sources
References in the record
- access.redhat.com/errata/RHSA-2023:6209
- access.redhat.com/errata/RHSA-2023:6744
- access.redhat.com/errata/RHSA-2023:7371
And 22 more references. See all after sign-in
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