Improper access control in Linux kernel - CVE-2026-68166

Vulnerability identifier: #VU142139

CSH Severity: Low

CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-68166

CWE-ID: CWE-284

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to inject chosen return addresses.

The vulnerability exists due to improper access control in userfaultfd registration for virtual memory areas when registering shadow stack or special VMAs. A local user can register a shadow stack VMA with userfaultfd and inject a page with chosen return addresses via UFFDIO_COPY to inject chosen return addresses.

The issue involves shadow stack VMAs, and special VMAs are also affected in cases where a driver implements vm_uffd_ops.

Linux kernel
Debian Linux
SUSE Linux Enterprise Workstation Extension 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise High Availability Extension 15
SUSE Linux Enterprise Desktop 15
Red Hat CodeReady Linux Builder for ARM 64 - Extended Update Support
Red Hat CodeReady Linux Builder for IBM z Systems - Extended Update Support
Red Hat CodeReady Linux Builder for Power, little endian - Extended Update Support
Red Hat CodeReady Linux Builder for x86_64 - Extended Update Support
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for x86_64
Basesystem Module
Development Tools Module
Legacy Module
Public Cloud Module
SUSE Linux Enterprise Live Patching
kernel-livepatch-SLE15-SP7_Update_21-debugsource
kernel-livepatch-6_4_0-150700_53_81-default-debuginfo
kernel-livepatch-6_4_0-150700_53_81-default
kernel-default-livepatch
kernel-64kb-devel
kernel-64kb-devel-debuginfo
kernel-64kb-debugsource
kernel-docs
kernel-syms
kernel-obs-build
kernel-obs-build-debugsource
kernel-source
reiserfs-kmp-default
reiserfs-kmp-default-debuginfo
kernel-64kb-debuginfo
kernel-default-livepatch-devel
kernel-azure
kernel-azure-devel
kernel-azure-debugsource
kernel-azure-debuginfo
kernel-azure-devel-debuginfo
kernel-default-extra-debuginfo
kernel-default-extra
kernel-64kb
gfs2-kmp-default
cluster-md-kmp-default
kernel-default-debuginfo
ocfs2-kmp-default-debuginfo
dlm-kmp-default-debuginfo
ocfs2-kmp-default
gfs2-kmp-default-debuginfo
dlm-kmp-default
cluster-md-kmp-default-debuginfo
kernel-default-debugsource
kernel-default
kernel-default-devel-debuginfo
kernel-default-devel
kernel-macros
kernel-devel
kernel-zfcpdump
kernel-zfcpdump-debugsource
kernel-zfcpdump-debuginfo
kernel-default-base
kernel (Red Hat package)
linux (Debian package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
kernel-livepatch-SLE15-SP7_Update_21-debugsource - 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-6_4_0-150700_53_81-default - update to 1-150700.15.3.1
kernel-default-livepatch - update to 6.4.0-150700.53.81.1
kernel-64kb-devel - update to 6.4.0-150700.53.81.1
kernel-64kb-devel-debuginfo - update to 6.4.0-150700.53.81.1
kernel-64kb-debugsource - update to 6.4.0-150700.53.81.1
kernel-docs - update to 6.4.0-150700.53.81.1
kernel-syms - update to 6.4.0-150700.53.81.1
kernel-obs-build - update to 6.4.0-150700.53.81.1
kernel-obs-build-debugsource - update to 6.4.0-150700.53.81.1
kernel-source - update to 6.4.0-150700.53.81.1
reiserfs-kmp-default - update to 6.4.0-150700.53.81.1
reiserfs-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
kernel-64kb-debuginfo - update to 6.4.0-150700.53.81.1
kernel-default-livepatch-devel - update to 6.4.0-150700.53.81.1
kernel-azure - update to 6.4.0-150700.53.81.1
kernel-azure-devel - update to 6.4.0-150700.53.81.1
kernel-azure-debugsource - update to 6.4.0-150700.53.81.1
kernel-azure-debuginfo - update to 6.4.0-150700.53.81.1
kernel-azure-devel-debuginfo - update to 6.4.0-150700.53.81.1
kernel-default-extra-debuginfo - update to 6.4.0-150700.53.81.1
kernel-default-extra - update to 6.4.0-150700.53.81.1
kernel-64kb - update to 6.4.0-150700.53.81.1
gfs2-kmp-default - update to 6.4.0-150700.53.81.1
cluster-md-kmp-default - update to 6.4.0-150700.53.81.1
kernel-default-debuginfo - update to 6.4.0-150700.53.81.1
ocfs2-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
dlm-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
ocfs2-kmp-default - update to 6.4.0-150700.53.81.1
gfs2-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
dlm-kmp-default - update to 6.4.0-150700.53.81.1
cluster-md-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
kernel-default-debugsource - update to 6.4.0-150700.53.81.1
kernel-default - update to 6.4.0-150700.53.81.1
kernel-default-devel-debuginfo - update to 6.4.0-150700.53.81.1
kernel-default-devel - update to 6.4.0-150700.53.81.1
kernel-macros - update to 6.4.0-150700.53.81.1
kernel-devel - update to 6.4.0-150700.53.81.1
kernel-zfcpdump - update to 6.4.0-150700.53.81.1
kernel-zfcpdump-debugsource - update to 6.4.0-150700.53.81.1
kernel-zfcpdump-debuginfo - update to 6.4.0-150700.53.81.1
kernel-default-base - update to 6.4.0-150700.53.81.1.150700.17.45.1
kernel (Red Hat package) - addressed in versions 6.12.0-55.105.1.el10_0, 6.12.0-211.50.1.el10_2
linux (Debian package) - update to 6.12.105-1

• https://git.kernel.org/stable/c/0c26202b157f1efc3cd2f26f5c30f59b508a6a5d
• https://git.kernel.org/stable/c/165613191ad9d034bf17c00e3a142f9561597ec5
• https://git.kernel.org/stable/c/3c58f641e813c3c71039f8fd4d4e2a3aab713288

• Improper access control in Linux kernel mm
• Debian update for linux
• Red Hat Enterprise Linux 10 update for kernel
• Red Hat Enterprise Linux 10 update for kernel
• SUSE update for the Linux Kernel