Unauthorized ADS access via worker credential reuse
Published Jul 25, 2026 · Updated Jul 25, 2026
Privilege management flaw in Linux Kernel ksmbd allows remote attackers to read, replace, or truncate alternate data streams. The stream read and write paths in fs/smb/server/vfs.c invoke VFS xattr helpers under the current privileged worker credentials instead of the credentials captured when the handle was opened. An exposed, guest-enabled streams share permits unauthenticated access, allowing inode and LSM checks to be bypassed for selected stream data.
Summary
What happened
Privilege management flaw in Linux Kernel ksmbd allows remote attackers to read, replace, or truncate alternate data streams. The stream read and write paths in fs/smb/server/vfs.c invoke VFS xattr helpers under the current privileged worker credentials instead of the credentials captured when the handle was opened. An exposed, guest-enabled streams share permits unauthenticated access, allowing inode and LSM checks to be bypassed for selected stream data.
The record
- CVE
- CVE-2026-64391
- Published
- Jul 25, 2026
- Updated
- Jul 25, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- T1210
- 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 <6.12.96
- Affected versionversion=0 <6.18.39
- Affected versionversion=0 <7.1.4
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2b4592cea214683de0f2ce6f8c22c097fb0ea1ab
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <52a56cf53ec834c44ac1b4d16d585f26613ee5ce
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a8f5d39971bbad9340d49cd41b0e2da9452a649d
- Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <baa5e094886fffa7e6272edcb5e08be5ce28262c
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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