Improper access control in Linux kernel - CVE-2026-31392

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Main Vulnerability Database Vulnerabilities #VU124889

Improper access control in Linux kernel - CVE-2026-31392

Published: April 6, 2026


Vulnerability identifier: #VU124889
CSH Severity: Low
CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-31392
CWE-ID: CWE-284
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to gain access to a share using incorrect credentials.

The vulnerability exists due to improper access control in the smb client session matching logic when processing cifs mounts with sec=krb5 and a username mount option. A local user can mount another share with a different username option to gain access to a share using incorrect credentials.

The issue occurs when Kerberos mounts reuse an SMB session from a previous mount even though a different username was specified, which can cause a mount that should fail with -ENOKEY to proceed with the first user's session.


Affected software

Linux kernel
Debian Linux
SUSE Linux Enterprise Workstation Extension 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise High Availability Extension 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Live Patching
Legacy Module
Public Cloud Module
Development Tools Module
Basesystem Module
SUSE Real Time Module
openEuler
Ubuntu
kernel-livepatch-6_4_0-150700_7_54-rt
kernel-livepatch-SLE15-SP7-RT_Update_15-debugsource
kernel-livepatch-6_4_0-150700_7_54-rt-debuginfo
kernel-livepatch-SLE15-SP7_Update_15-debugsource
kernel-livepatch-6_4_0-150700_53_55-default-debuginfo
kernel-livepatch-6_4_0-150700_53_55-default
bpftool
kernel
python3-perf-debuginfo
python3-perf
perf-debuginfo
kernel-tools-devel
bpftool-debuginfo
kernel-debuginfo
kernel-debugsource
kernel-devel
kernel-headers
kernel-source
kernel-tools
kernel-tools-debuginfo
perf
linux (Debian package)
gfs2-kmp-rt
kernel-rt
kernel-source-rt
kernel-devel-rt
gfs2-kmp-rt-debuginfo
cluster-md-kmp-rt
ocfs2-kmp-rt
kernel-syms-rt
dlm-kmp-rt
ocfs2-kmp-rt-debuginfo
kernel-rt-devel
dlm-kmp-rt-debuginfo
kernel-rt-devel-debuginfo
kernel-rt-debuginfo
cluster-md-kmp-rt-debuginfo
kernel-rt-debugsource
kernel-zfcpdump-debuginfo
kernel-zfcpdump-debugsource
kernel-docs
kernel-syms
kernel-obs-build
kernel-zfcpdump
kernel-obs-build-debugsource
reiserfs-kmp-default-debuginfo
reiserfs-kmp-default
kernel-azure
kernel-azure-debugsource
kernel-azure-debuginfo
kernel-azure-devel
kernel-default-extra-debuginfo
kernel-default-extra
kernel-default-livepatch
kernel-default-livepatch-devel
kernel-azure-devel-debuginfo
kernel-macros
cluster-md-kmp-default
kernel-default-debuginfo
ocfs2-kmp-default-debuginfo
dlm-kmp-default-debuginfo
kernel-default-debugsource
gfs2-kmp-default
gfs2-kmp-default-debuginfo
dlm-kmp-default
cluster-md-kmp-default-debuginfo
kernel-default
ocfs2-kmp-default
kernel-default-devel
kernel-default-devel-debuginfo
kernel-64kb-debuginfo
kernel-64kb-devel
kernel-64kb-debugsource
kernel-64kb-devel-debuginfo
kernel-64kb
kernel-default-base
kernel-extra-modules
linux (Ubuntu package)
linux-fips (Ubuntu package)
linux-hwe-6.8 (Ubuntu package)
linux-ibm (Ubuntu package)
linux-oracle-6.8 (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-aws-6.8 (Ubuntu package)
linux-aws (Ubuntu package)
linux-raspi (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux-azure-fde-6.8 (Ubuntu package)
linux-azure (Ubuntu package)
linux-azure-fips (Ubuntu package)
linux-gcp-fips (Ubuntu package)

How to mitigate CVE-2026-31392

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
kernel-livepatch-6_4_0-150700_7_54-rt - update to 1-150700.1.3.1
kernel-livepatch-SLE15-SP7-RT_Update_15-debugsource - update to 1-150700.1.3.1
kernel-livepatch-6_4_0-150700_7_54-rt-debuginfo - update to 1-150700.1.3.1
kernel-livepatch-SLE15-SP7_Update_15-debugsource - update to 1-150700.15.3.1
kernel-livepatch-6_4_0-150700_53_55-default-debuginfo - update to 1-150700.15.3.1
kernel-livepatch-6_4_0-150700_53_55-default - update to 1-150700.15.3.1
bpftool - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
python3-perf-debuginfo - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
python3-perf - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
perf-debuginfo - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-tools-devel - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
bpftool-debuginfo - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-debuginfo - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-debugsource - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-devel - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-headers - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-source - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-tools - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-tools-debuginfo - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
perf - addressed in versions 5.10.0-310.0.0.213, 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
linux (Debian package) - addressed in versions 6.1.170-1, 6.12.85-1
gfs2-kmp-rt - update to 6.4.0-150700.7.54.1
kernel-rt - update to 6.4.0-150700.7.54.1
kernel-source-rt - update to 6.4.0-150700.7.54.1
kernel-devel-rt - update to 6.4.0-150700.7.54.1
gfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.54.1
cluster-md-kmp-rt - update to 6.4.0-150700.7.54.1
ocfs2-kmp-rt - update to 6.4.0-150700.7.54.1
kernel-syms-rt - update to 6.4.0-150700.7.54.1
dlm-kmp-rt - update to 6.4.0-150700.7.54.1
ocfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.54.1
kernel-rt-devel - update to 6.4.0-150700.7.54.1
dlm-kmp-rt-debuginfo - update to 6.4.0-150700.7.54.1
kernel-rt-devel-debuginfo - update to 6.4.0-150700.7.54.1
kernel-rt-debuginfo - update to 6.4.0-150700.7.54.1
cluster-md-kmp-rt-debuginfo - update to 6.4.0-150700.7.54.1
kernel-rt-debugsource - update to 6.4.0-150700.7.54.1
kernel-zfcpdump-debuginfo - update to 6.4.0-150700.53.55.1
kernel-zfcpdump-debugsource - update to 6.4.0-150700.53.55.1
kernel-docs - update to 6.4.0-150700.53.55.1
kernel-syms - update to 6.4.0-150700.53.55.1
kernel-obs-build - update to 6.4.0-150700.53.55.1
kernel-zfcpdump - update to 6.4.0-150700.53.55.1
kernel-obs-build-debugsource - update to 6.4.0-150700.53.55.1
kernel-source - update to 6.4.0-150700.53.55.1
reiserfs-kmp-default-debuginfo - update to 6.4.0-150700.53.55.1
reiserfs-kmp-default - update to 6.4.0-150700.53.55.1
kernel-azure - update to 6.4.0-150700.53.55.1
kernel-azure-debugsource - update to 6.4.0-150700.53.55.1
kernel-azure-debuginfo - update to 6.4.0-150700.53.55.1
kernel-azure-devel - update to 6.4.0-150700.53.55.1
kernel-default-extra-debuginfo - update to 6.4.0-150700.53.55.1
kernel-default-extra - update to 6.4.0-150700.53.55.1
kernel-default-livepatch - update to 6.4.0-150700.53.55.1
kernel-default-livepatch-devel - update to 6.4.0-150700.53.55.1
kernel-azure-devel-debuginfo - update to 6.4.0-150700.53.55.1
kernel-devel - update to 6.4.0-150700.53.55.1
kernel-macros - update to 6.4.0-150700.53.55.1
cluster-md-kmp-default - update to 6.4.0-150700.53.55.1
kernel-default-debuginfo - update to 6.4.0-150700.53.55.1
ocfs2-kmp-default-debuginfo - update to 6.4.0-150700.53.55.1
dlm-kmp-default-debuginfo - update to 6.4.0-150700.53.55.1
kernel-default-debugsource - update to 6.4.0-150700.53.55.1
gfs2-kmp-default - update to 6.4.0-150700.53.55.1
gfs2-kmp-default-debuginfo - update to 6.4.0-150700.53.55.1
dlm-kmp-default - update to 6.4.0-150700.53.55.1
cluster-md-kmp-default-debuginfo - update to 6.4.0-150700.53.55.1
kernel-default - update to 6.4.0-150700.53.55.1
ocfs2-kmp-default - update to 6.4.0-150700.53.55.1
kernel-default-devel - update to 6.4.0-150700.53.55.1
kernel-default-devel-debuginfo - update to 6.4.0-150700.53.55.1
kernel-64kb-debuginfo - update to 6.4.0-150700.53.55.1
kernel-64kb-devel - update to 6.4.0-150700.53.55.1
kernel-64kb-debugsource - update to 6.4.0-150700.53.55.1
kernel-64kb-devel-debuginfo - update to 6.4.0-150700.53.55.1
kernel-64kb - update to 6.4.0-150700.53.55.1
kernel-default-base - update to 6.4.0-150700.53.55.1.150700.17.33.1
kernel-extra-modules - update to 6.6.0-145.3.14.145
linux (Ubuntu package) - addressed in versions 6.8.0-136.136, 6.8.0-1046.50, 6.8.0-1059.67, 6.8.0-1064.72, 6.8.0-1064.72~22.04.1, 6.8.1-1056.57, 6.8.1-1056.57~22.04.2
linux-fips (Ubuntu package) - addressed in versions 6.8.0-136.136+fips2, 6.8.0-136.136.2, 6.8.0-136.136.2~22.04.1, 6.8.0-1058.61
linux-hwe-6.8 (Ubuntu package) - update to 6.8.0-136.136~22.04.1
linux-ibm (Ubuntu package) - addressed in versions 6.8.0-1030.31, 6.8.0-1033.34, 6.8.0-1061.62, 6.8.0-1061.62~22.04.1
linux-oracle-6.8 (Ubuntu package) - update to 6.8.0-1058.61~22.04.1
linux-nvidia (Ubuntu package) - addressed in versions 6.8.0-1059.62, 6.8.0-1059.62.1, 6.8.0-1059.62~22.04.1
linux-aws-6.8 (Ubuntu package) - addressed in versions 6.8.0-1061.64+fips1, 6.8.0-1061.64~22.04.1
linux-aws (Ubuntu package) - update to 6.8.0-1061.64+1
linux-raspi (Ubuntu package) - addressed in versions 6.8.0-1061.65, 6.8.0-2050.52
linux-azure-fde (Ubuntu package) - update to 6.8.0-1062.69
linux-azure-fde-6.8 (Ubuntu package) - update to 6.8.0-1062.69~22.04.1
linux-azure (Ubuntu package) - addressed in versions 6.8.0-1063.71, 6.8.0-1063.71~22.04.1
linux-azure-fips (Ubuntu package) - update to 6.8.0-1063.71+fips2
linux-gcp-fips (Ubuntu package) - update to 6.8.0-1064.72+fips1

External References

Related Security Bulletins