SB20260625245 - Improper access control in Linux kernel smb server

Description

This security bulletin contains information about 1 vulnerability.

1) Improper access control (CVE-ID: CVE-2026-52944)

CWE-ID: CWE-284 - Improper Access Control

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a remote user to bypass permission checks and modify file sparse attributes.

The vulnerability exists due to improper access control in fsctl_set_sparse() when handling FSCTL_SET_SPARSE requests. A remote user can send a crafted FSCTL_SET_SPARSE request on an opened file to bypass permission checks and modify file sparse attributes.

The issue affects both clients on read-only shares and clients on writable shares that lack FILE_WRITE_DATA or FILE_WRITE_ATTRIBUTES access.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/3127a884525dc8ca4def73254bfcd3ccef0bf812
• https://git.kernel.org/stable/c/aef151bcfa494bfe983669de2726734b534adb73
• https://git.kernel.org/stable/c/cc57232cae23c0df91b4a59d0f519141ce9b5b02
• https://git.kernel.org/stable/c/de9eb0b44fa9123170e6245b49638e0e453c10f8