File-hole corruption via post-punch dirty writeback
Published Sep 24, 2026 · Updated Sep 24, 2026
Data-integrity flaw in the Linux SMB client before 6.12.111 and 6.18.53 allows local users to refill punched file regions. smb3_punch_hole issues FSCTL_SET_ZERO_DATA without first flushing a dirty folio, so later writeback repopulates the intended hole. Triggering the flaw requires write access to a punch-hole-capable SMB mount and a buffered write whose dirty folio spans the punched range; the result is incorrect hole and data reporting rather than disclosed cross-user code execution.
Summary
What happened
Data-integrity flaw in the Linux SMB client before 6.12.111 and 6.18.53 allows local users to refill punched file regions. smb3_punch_hole issues FSCTL_SET_ZERO_DATA without first flushing a dirty folio, so later writeback repopulates the intended hole. Triggering the flaw requires write access to a punch-hole-capable SMB mount and a buffered write whose dirty folio spans the punched range; the result is incorrect hole and data reporting rather than disclosed cross-user code execution.
The record
- CVE
- CVE-2026-93794
- Published
- Sep 24, 2026
- Updated
- Sep 24, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 24, 2026CVE publishedPublication date reported by the CVE source.
- Sep 24, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <6.12.111
- Affected versionversion=0 <6.18.53
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <39562a56cdb515f6635c3e7bfe6629439b18a169
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6c265aca08155e519a8f6f6071c59dff4f535f70
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d7d2adcd022baade5cab65ca492ce63421ce3a6e
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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
No sourced classifications are available.
Public exploit references
- xfs_io SMB hole-punch reproducerproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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