Unauthorized file changes via worker credentials
Published Jul 25, 2026 · Updated Jul 25, 2026
Improper authorization in Linux kernel ksmbd allows remote attackers to modify SMB-served filesystem objects through SMB2 SET_INFO. The SET_INFO dispatch checks the handle access mask, then invokes path-based VFS helpers under the ksmbd worker credentials instead of the credentials captured when the handle opened, bypassing owner, inode-permission, and LSM checks. Reachability requires an enabled, network-accessible ksmbd service and an SMB handle accepted for the requested SET_INFO class.
Summary
What happened
Improper authorization in Linux kernel ksmbd allows remote attackers to modify SMB-served filesystem objects through SMB2 SET_INFO. The SET_INFO dispatch checks the handle access mask, then invokes path-based VFS helpers under the ksmbd worker credentials instead of the credentials captured when the handle opened, bypassing owner, inode-permission, and LSM checks. Reachability requires an enabled, network-accessible ksmbd service and an SMB handle accepted for the requested SET_INFO class.
The record
- CVE
- CVE-2026-64393
- Published
- Jul 25, 2026
- Updated
- Jul 25, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- T1565.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 25, 2026CVE publishedPublication date reported by the CVE source.
- Jul 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <6.1.178
- Affected versionversion=0 <6.12.96
- Affected versionversion=0 <6.18.39
- Affected versionversion=0 <6.6.145
- Affected versionversion=0 <7.1.4
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0ce682867fd506f61f40c76bde7e4205bde34e87
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <20ee516a62989a8d505ee432f9e59525ea23984e
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5cbabf3a71575cd31bc7785d92d4ab42338a654b
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <8cc9ec711f5255167247a9ab6a7179b787426ed7
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b35afd5cf8fab236ef21117e42ee45691d4ffa7b
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b383bcad3d2fe634b26efbce53e22bbb5753a520
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
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Technologies
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Your stack
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