Improper access control in Linux kernel - CVE-2026-68457
Published: August 17, 2026
Vulnerability identifier: #VU143618
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-68457
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 file permission checks.
The vulnerability exists due to improper access control in ksmbd FSCTL mutation handlers when processing SET_SPARSE, SET_ZERO_DATA, or SET_COMPRESSION operations on an open SMB handle. A remote user can invoke these operations so they are performed with ksmbd worker credentials to bypass intended file permission checks.
The issue arises because helper calls may independently revalidate inode permissions, ownership, or LSM policy instead of relying solely on the SMB handle access mask.
Affected software
Linux kernel
How to mitigate CVE-2026-68457
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
External References
- https://git.kernel.org/stable/c/1e112c47ec5dd1942e2d4ca6e8e9b712238e20c2
- https://git.kernel.org/stable/c/a8c18434e1f0d9f7989170bdb0490c0160baf065
- https://git.kernel.org/stable/c/c6394bcaf254c5baf9aff43376020be5db6d3316
- https://git.kernel.org/stable/c/cfb2c6f71d61ed807c9d7a7af331d406f1f31877
- https://git.kernel.org/stable/c/e205f3e7e8c31a47cd11efb6cf663a527177e432
- https://git.kernel.org/stable/c/fb1cae6302d58414ddf029e3f642711bd30243f7