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

Why this deserves its current priority

CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

Affected software not mapped in the current feed; confirm the named product and version against your inventory.

Recommended response

Confirm exposure. Identify whether the named product or interface exists in your inventory, then review the linked upstream references for affected versions and vendor guidance.

Evidence timeline and material changes

Published upstream
Nov 3, 2023
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Nov 7, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Nov 7, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.

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