Improper access control in Linux kernel - CVE-2026-64393
Published: July 27, 2026
Vulnerability identifier: #VU139580
CSH Severity: Medium
CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64393
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to bypass intended permission checks.
The vulnerability exists due to improper access control in SMB2 SET_INFO handlers when processing SET_INFO requests. A remote user can send a specially crafted SET_INFO request to bypass intended permission checks.
The issue arises because path-based VFS helpers perform permission and LSM checks using worker credentials instead of the credentials captured when the file handle was opened.
Affected software
Linux kernel
How to mitigate CVE-2026-64393
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
External References
- https://git.kernel.org/stable/c/0ce682867fd506f61f40c76bde7e4205bde34e87
- https://git.kernel.org/stable/c/20ee516a62989a8d505ee432f9e59525ea23984e
- https://git.kernel.org/stable/c/5cbabf3a71575cd31bc7785d92d4ab42338a654b
- https://git.kernel.org/stable/c/8cc9ec711f5255167247a9ab6a7179b787426ed7
- https://git.kernel.org/stable/c/b35afd5cf8fab236ef21117e42ee45691d4ffa7b
- https://git.kernel.org/stable/c/b383bcad3d2fe634b26efbce53e22bbb5753a520