Authenticated file truncation via mismatched access check
Published Nov 3, 2023 · Updated Nov 20, 2025
Improper permission enforcement in Samba on affected Red Hat Enterprise Linux releases allows remote authenticated users to truncate files. When acl_xattr:ignore system acls is enabled, Samba checks the client's stated read-only request instead of the implicit read-write access required by an OVERWRITE disposition. An authenticated SMB user who can open a file can reduce it to zero bytes despite lacking write permission; the default setting is not affected.
Summary
What happened
Improper permission enforcement in Samba on affected Red Hat Enterprise Linux releases allows remote authenticated users to truncate files. When acl_xattr:ignore system acls is enabled, Samba checks the client's stated read-only request instead of the implicit read-write access required by an OVERWRITE disposition. An authenticated SMB user who can open a file can reduce it to zero bytes despite lacking write permission; the default setting is not affected.
The record
- CVE
- CVE-2023-4091
- Published
- Nov 3, 2023
- Updated
- Nov 20, 2025
- Vendor
- Red Hat
- Product
- Red Hat Enterprise Linux 8
- Classifications
- CWE-276, T1485
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Nov 3, 2023CVE publishedPublication date reported by the CVE source.
- Nov 20, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Public exploit references
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Technologies
Your stack
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Your stack
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