Unspecified impact via zero-size lock-range underflow
Published Jan 13, 2026 · Updated Jan 13, 2026
Integer underflow in Linux kernel ksmbd allows attackers to trigger an invalid lock-range check via a zero-size truncation request. ksmbd_vfs_truncate passes i_size as the range start and size - 1 as the inclusive end when size equals i_size, so an empty file turns the end offset into -1. Reachability requires the ksmbd SMB server and permission to truncate a shared file; Linux has not published the resulting security impact.
Summary
What happened
Integer underflow in Linux kernel ksmbd allows attackers to trigger an invalid lock-range check via a zero-size truncation request. ksmbd_vfs_truncate passes i_size as the range start and size - 1 as the inclusive end when size equals i_size, so an empty file turns the end offset into -1. Reachability requires the ksmbd SMB server and permission to truncate a shared file; Linux has not published the resulting security impact.
The record
- CVE
- CVE-2025-68786
- Published
- Jan 13, 2026
- Updated
- Jan 13, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- Unavailable
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Jan 13, 2026CVE publishedPublication date reported by the CVE source.
- Jan 13, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <52fcbb92e0d3acfd1448b2a43b6595d540da5295
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <571204e4758a528fbd67330bd4b0dfbdafb33dd8
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5d510ac31626ed157d2182149559430350cf2104
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a6f4cfa3783804336491e0edcb250c25f9b59d33
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <da29cd197246c85c0473259f1cad897d9d28faea
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
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Public exploit references
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Technologies
Your stack
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Your stack
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