Improper access control in Linux kernel - CVE-2026-68457

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Main Vulnerability Database Vulnerabilities #VU143618

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
Ubuntu
linux-nvidia-tegra (Ubuntu package)
linux (Ubuntu package)
linux-gke (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-gcp (Ubuntu package)

How to mitigate CVE-2026-68457

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-nvidia-tegra (Ubuntu package) - update to 6.8.0-1035.38
linux (Ubuntu package) - addressed in versions 7.0.0-34.34, 7.0.0-34.34.1, 7.0.0-34.34~24.04.1, 7.0.0-1012.12~24.04.1, 7.0.0-1013.13, 7.0.0-1013.13~24.04.1, 7.0.0-1014.14, 7.0.0-1020.20
linux-gke (Ubuntu package) - update to 7.0.0-1007.8
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1012.12~24.04.1
linux-gcp (Ubuntu package) - addressed in versions 7.0.0-1013.13, 7.0.0-1013.13~24.04.1, 7.0.0-1014.14

External References

Related Security Bulletins