DACL corruption via wrapped rewrite size
Published Sep 25, 2026 · Updated Sep 25, 2026
Integer overflow in the Linux SMB client allows local users to send corrupted DACLs during chmod or chown operations. The replace_sids_and_copy_aces() and set_chmod_dacl() functions accumulate an expanded DACL size in a 16-bit value, which wraps and makes the recorded size and ACE offset invalid. Reachability requires a CIFS DACL rewrite exceeding 65,535 bytes; the malformed DACL remains within its allocated buffer but is transmitted to the SMB server.
Summary
What happened
Integer overflow in the Linux SMB client allows local users to send corrupted DACLs during chmod or chown operations. The replace_sids_and_copy_aces() and set_chmod_dacl() functions accumulate an expanded DACL size in a 16-bit value, which wraps and makes the recorded size and ACE offset invalid. Reachability requires a CIFS DACL rewrite exceeding 65,535 bytes; the malformed DACL remains within its allocated buffer but is transmitted to the SMB server.
The record
- CVE
- CVE-2026-97559
- Published
- Sep 25, 2026
- Updated
- Sep 25, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 25, 2026CVE publishedPublication date reported by the CVE source.
- Sep 25, 2026Record 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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- Affected versionversion=5.12
- Affected versionversion=f5065508897a922327f32223082325d10b069ebc <2ef532a01f44687f5b95001e88247cf05bff9892
- Affected versionversion=f5065508897a922327f32223082325d10b069ebc <d05045177a855386bca5e1909e08d06290e6e3b3
- Affected versionversion=f5065508897a922327f32223082325d10b069ebc <ee13d687d06a6fbb2008625dd560c654231b28e0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
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Public exploit references
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Technologies
Your stack
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