Improper access control in Linux kernel - CVE-2026-52944

Vulnerability identifier: #VU135434

CSH Severity: Low

CVSS v4: 5.3 [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]

CVE-ID: CVE-2026-52944

CWE-ID: CWE-284

Exploitation vector: Remote access

Exploit availability: No public exploit available

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.

Linux kernel
Debian Linux
Ubuntu
linux (Debian package)
linux (Ubuntu package)
linux-ibm (Ubuntu package)
linux-azure (Ubuntu package)
linux-aws (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-azure-7.0 (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Debian package) - update to 6.12.111-1
linux (Ubuntu package) - addressed in versions 7.0.0-28.28, 7.0.0-28.28.1, 7.0.0-1003.4, 7.0.0-1008.8
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1009.9
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-azure-7.0 (Ubuntu package) - update to 7.0.0-1014.14~24.04.1
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

• 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

• Improper access control in Linux kernel smb server
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-nvidia
• Ubuntu update for linux-gcp-7.0
• Ubuntu update for linux-oracle-7.0
• Ubuntu update for linux-azure-7.0
• Debian update for linux