CVE-2023-4091
Published: 03 November 2023
Summary
CVE-2023-4091 is a medium-severity Incorrect Default Permissions (CWE-276) vulnerability in Samba Samba. Its CVSS base score is 6.5 (Medium).
Operationally, ranked in the top 36.4% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-53981
Vulnerability details
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…
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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.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Access control policy can specify and enforce secure default permissions for resources.
Guides setting of default permissions to the minimum required level.
Establishes requirements for appropriate default permissions on system resources as part of configuration management.
Baseline establishment and updates on install/upgrade ensure correct default permissions rather than insecure ones.
Requiring the most restrictive settings instead of defaults prevents incorrect default permissions on resources.
Requires documented processes that include setting and maintaining correct default permissions for configuration items.
Requires addressing secure default permissions in physical and environmental protection controls.
Tailoring explicitly overrides or scopes default permission assignments in the baseline to match the system's actual risk and operational needs.