Improper access control in Linux kernel - CVE-2026-64388

Vulnerability identifier: #VU139575

CSH Severity: Low

CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-64388

CWE-ID: CWE-284

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to bypass ownership and group changes.

The vulnerability exists due to improper access control in cifs_setattr_nounix() when processing chown and chgrp operations on mounts using SMB3 POSIX Extensions. A local user can change file ownership or group attributes in a way that is ignored to bypass ownership and group changes.

The issue occurs only when SMB3 POSIX Extensions are used without the relevant ACL or SID-based mount options enabled.

Linux kernel
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
Debian Linux
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise High Performance Computing 12
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Workstation Extension 15
SUSE Linux Enterprise High Availability Extension 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Micro
SUSE Linux Micro Extras
SUSE Linux Enterprise Live Patching
SUSE Real Time Module
Public Cloud Module
Legacy Module
Development Tools Module
Basesystem Module
openEuler
Ubuntu
kgraft-patch-4_12_14-122_333-default
kernel-livepatch-6_4_0-150700_7_75-rt-debuginfo
kernel-livepatch-6_4_0-150700_7_75-rt
kernel-livepatch-SLE15-SP7-RT_Update_20-debugsource
kernel-livepatch-6_4_0-150700_53_81-default
kernel-livepatch-6_4_0-150700_53_81-default-debuginfo
kernel-livepatch-SLE15-SP7_Update_21-debugsource
ocfs2-kmp-default-debuginfo
kernel-default-man
kernel-devel
kernel-source
kernel-macros
kernel-default-devel-debuginfo
gfs2-kmp-default
gfs2-kmp-default-debuginfo
kernel-default-devel
cluster-md-kmp-default-debuginfo
kernel-default-base
kernel-default
kernel-default-kgraft
kernel-default-debugsource
kernel-default-kgraft-devel
kernel-default-debuginfo
dlm-kmp-default
dlm-kmp-default-debuginfo
ocfs2-kmp-default
cluster-md-kmp-default
kernel-default-base-debuginfo
kernel-syms
bpftool
kernel
bpftool-debuginfo
kernel-debuginfo
kernel-debugsource
kernel-tools
kernel-tools-debuginfo
kernel-tools-devel
perf
perf-debuginfo
python2-perf
python3-perf-debuginfo
python3-perf
python2-perf-debuginfo
kernel-headers
kernel-rt-debugsource
kernel-rt-debuginfo
kernel-rt
kernel-devel-rt
kernel-source-rt
kernel-kvmsmall
kernel-default-livepatch
kernel-kvmsmall-debugsource
kernel-kvmsmall-debuginfo
kernel-obs-build-debugsource
kernel-rt-livepatch
kernel-obs-build
kernel-64kb-devel
kernel-64kb-debugsource
kernel-64kb
kernel-rt-devel-debuginfo
ocfs2-kmp-rt
gfs2-kmp-rt-debuginfo
dlm-kmp-rt
kernel-rt-devel
cluster-md-kmp-rt
kernel-syms-rt
ocfs2-kmp-rt-debuginfo
gfs2-kmp-rt
dlm-kmp-rt-debuginfo
cluster-md-kmp-rt-debuginfo
kernel-default-extra
kernel-zfcpdump-debuginfo
kernel-docs
kernel-64kb-devel-debuginfo
kernel-64kb-debuginfo
kernel-zfcpdump-debugsource
kernel-zfcpdump
reiserfs-kmp-default
kernel-default-extra-debuginfo
kernel-azure-devel-debuginfo
kernel-azure-debuginfo
kernel-azure-debugsource
kernel-azure-devel
kernel-azure
kernel-default-livepatch-devel
reiserfs-kmp-default-debuginfo
linux-nvidia-tegra (Ubuntu package)
linux (Debian package)
linux (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-azure (Ubuntu package)
linux-ibm (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-azure-7.0 (Ubuntu package)
linux-nvidia-7.0 (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-raspi (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
kgraft-patch-4_12_14-122_333-default - update to 1-8.3.3
kernel-livepatch-6_4_0-150700_7_75-rt-debuginfo - update to 1-150700.1.3.1
kernel-livepatch-6_4_0-150700_7_75-rt - update to 1-150700.1.3.1
kernel-livepatch-SLE15-SP7-RT_Update_20-debugsource - update to 1-150700.1.3.1
kernel-livepatch-6_4_0-150700_53_81-default - update to 1-150700.15.3.1
kernel-livepatch-6_4_0-150700_53_81-default-debuginfo - update to 1-150700.15.3.1
kernel-livepatch-SLE15-SP7_Update_21-debugsource - update to 1-150700.15.3.1
ocfs2-kmp-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.81.1
kernel-default-man - update to 4.12.14-122.333.2
kernel-devel - addressed in versions 4.12.14-122.333.2, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-source - addressed in versions 4.12.14-122.333.2, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-macros - addressed in versions 4.12.14-122.333.2, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-default-devel-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-52.1, 6.4.0-150700.53.81.1
gfs2-kmp-default - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.81.1
gfs2-kmp-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.81.1
kernel-default-devel - addressed in versions 4.12.14-122.333.2, 6.4.0-52.1, 6.4.0-150700.53.81.1
cluster-md-kmp-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.81.1
kernel-default-base - addressed in versions 4.12.14-122.333.2, 6.4.0-52.1.21.35, 6.4.0-52.1.21.36, 6.4.0-150700.53.81.1.150700.17.45.1
kernel-default - addressed in versions 4.12.14-122.333.2, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-default-kgraft - update to 4.12.14-122.333.2
kernel-default-debugsource - addressed in versions 4.12.14-122.333.2, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-default-kgraft-devel - update to 4.12.14-122.333.2
kernel-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-52.1, 6.4.0-150700.53.81.1
dlm-kmp-default - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.81.1
dlm-kmp-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.81.1
ocfs2-kmp-default - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.81.1
cluster-md-kmp-default - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.81.1
kernel-default-base-debuginfo - update to 4.12.14-122.333.2
kernel-syms - addressed in versions 4.12.14-122.333.2, 6.4.0-52.1, 6.4.0-150700.53.81.1
bpftool - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
kernel - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
bpftool-debuginfo - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
kernel-debuginfo - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
kernel-debugsource - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
kernel-devel - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
kernel-source - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
kernel-tools - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
kernel-tools-debuginfo - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
kernel-tools-devel - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
perf - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
perf-debuginfo - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
python2-perf - update to 4.19.90-2608.3.0.0385
python3-perf-debuginfo - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
python3-perf - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-329.0.0.230
python2-perf-debuginfo - update to 4.19.90-2608.3.0.0385
kernel-headers - update to 5.10.0-329.0.0.230
kernel-rt-debugsource - addressed in versions 6.4.0-52.1, 6.4.0-150700.7.75.1
kernel-rt-debuginfo - addressed in versions 6.4.0-52.1, 6.4.0-150700.7.75.1
kernel-rt - addressed in versions 6.4.0-52.1, 6.4.0-150700.7.75.1
kernel-devel-rt - addressed in versions 6.4.0-52.1, 6.4.0-150700.7.75.1
kernel-source-rt - addressed in versions 6.4.0-52.1, 6.4.0-150700.7.75.1
kernel-kvmsmall - update to 6.4.0-52.1
kernel-default-livepatch - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-kvmsmall-debugsource - update to 6.4.0-52.1
kernel-kvmsmall-debuginfo - update to 6.4.0-52.1
kernel-obs-build-debugsource - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-rt-livepatch - update to 6.4.0-52.1
kernel-obs-build - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-64kb-devel - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-64kb-debugsource - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-64kb - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-rt-devel-debuginfo - update to 6.4.0-150700.7.75.1
ocfs2-kmp-rt - update to 6.4.0-150700.7.75.1
gfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.75.1
dlm-kmp-rt - update to 6.4.0-150700.7.75.1
kernel-rt-devel - update to 6.4.0-150700.7.75.1
cluster-md-kmp-rt - update to 6.4.0-150700.7.75.1
kernel-syms-rt - update to 6.4.0-150700.7.75.1
ocfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.75.1
gfs2-kmp-rt - update to 6.4.0-150700.7.75.1
dlm-kmp-rt-debuginfo - update to 6.4.0-150700.7.75.1
cluster-md-kmp-rt-debuginfo - update to 6.4.0-150700.7.75.1
kernel-default-extra - update to 6.4.0-150700.53.81.1
kernel-zfcpdump-debuginfo - update to 6.4.0-150700.53.81.1
kernel-docs - update to 6.4.0-150700.53.81.1
kernel-64kb-devel-debuginfo - update to 6.4.0-150700.53.81.1
kernel-64kb-debuginfo - update to 6.4.0-150700.53.81.1
kernel-zfcpdump-debugsource - update to 6.4.0-150700.53.81.1
kernel-zfcpdump - update to 6.4.0-150700.53.81.1
reiserfs-kmp-default - update to 6.4.0-150700.53.81.1
kernel-default-extra-debuginfo - update to 6.4.0-150700.53.81.1
kernel-azure-devel-debuginfo - update to 6.4.0-150700.53.81.1
kernel-azure-debuginfo - update to 6.4.0-150700.53.81.1
kernel-azure-debugsource - update to 6.4.0-150700.53.81.1
kernel-azure-devel - update to 6.4.0-150700.53.81.1
kernel-azure - update to 6.4.0-150700.53.81.1
kernel-default-livepatch-devel - update to 6.4.0-150700.53.81.1
reiserfs-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
linux-nvidia-tegra (Ubuntu package) - update to 6.8.0-1036.39+1
linux (Debian package) - update to 6.12.115-2
linux (Ubuntu package) - addressed in versions 7.0.0-31.31~24.04.1, 7.0.0-31.31, 7.0.0-31.31.1, 7.0.0-1006.7, 7.0.0-1011.11~24.04.1, 7.0.0-1012.12~24.04.1, 7.0.0-1012.12
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1011.11, 7.0.0-1014.14
linux-ibm (Ubuntu package) - update to 7.0.0-1013.13
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13
linux-azure-7.0 (Ubuntu package) - update to 7.0.0-1014.14~24.04.1
linux-nvidia-7.0 (Ubuntu package) - update to 7.0.0-1018.18~24.04.1
linux-nvidia (Ubuntu package) - update to 7.0.0-1018.18
linux-raspi (Ubuntu package) - update to 7.0.0-1019.19
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2018.18

• https://git.kernel.org/stable/c/550cfb8a81181331d4d0f76ab75ee58a0bf41e3e
• https://git.kernel.org/stable/c/760ef2c579c2609cf17fb1cd5392f64d42d43d33

• Improper access control in Linux kernel smb client
• openEuler 20.03 LTS SP4 update for kernel
• openEuler 22.03 LTS SP4 update for kernel
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux
• Ubuntu update for linux-gcp-7.0
• SUSE update for the Linux Kernel
• Ubuntu update for linux-oracle-7.0
• Ubuntu update for linux-azure
• Ubuntu update for linux-azure-7.0
• Ubuntu update for linux-nvidia
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-ibm
• Ubuntu update for linux-raspi
• Ubuntu update for linux-nvidia-7.0
• Ubuntu update for linux-nvidia-tegra
• SUSE update for the Linux Kernel
• SUSE update for the Linux Kernel
• SUSE update for the Linux Kernel
• SUSE update for the Linux Kernel
• SUSE update for the Linux Kernel
• Debian update for linux