Improper access control in Linux kernel - CVE-2026-31668

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Main Vulnerability Database Vulnerabilities #VU127730

Improper access control in Linux kernel - CVE-2026-31668

Published: April 25, 2026


Vulnerability identifier: #VU127730
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-2026-31668
CWE-ID: CWE-284
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to bypass routing policy restrictions.

The vulnerability exists due to improper access control in the seg6 lwtunnel dst_cache handling when processing input and output paths in different routing contexts. A local user can trigger packet processing through one path so that the other path reuses an incorrect cached destination to bypass routing policy restrictions.

The issue occurs because a single destination cache is shared between seg6_input_core() and seg6_output_core(), even though these paths may perform SID lookup under different routing contexts such as ingress-interface-based rules or VRF table separation.


Affected software

Linux kernel
Debian Linux
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Workstation Extension 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Availability Extension 15
SUSE Linux Enterprise Desktop 15
Ubuntu
Development Tools Module
Legacy Module
Public Cloud Module
SUSE Real Time Module
SUSE Linux Enterprise Live Patching
Basesystem Module
openEuler
linux (Ubuntu package)
linux-kvm (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-azure (Ubuntu package)
linux-raspi (Ubuntu package)
linux-oracle (Ubuntu package)
linux-lowlatency (Ubuntu package)
linux-gke (Ubuntu package)
linux-aws-5.15 (Ubuntu package)
linux-lowlatency-hwe-5.15 (Ubuntu package)
linux-hwe-5.15 (Ubuntu package)
linux-fips (Ubuntu package)
linux-azure-5.15 (Ubuntu package)
linux-nvidia-tegra (Ubuntu package)
linux-gkeop (Ubuntu package)
linux-nvidia-tegra-igx (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-realtime (Ubuntu package)
linux-intel-iotg (Ubuntu package)
linux-azure-fde-5.15 (Ubuntu package)
linux-ibm-5.15 (Ubuntu package)
linux-ibm (Ubuntu package)
linux-intel-iotg-5.15 (Ubuntu package)
linux-oracle-5.15 (Ubuntu package)
linux-gcp-5.15 (Ubuntu package)
linux-nvidia-tegra-5.15 (Ubuntu package)
linux-xilinx-zynqmp (Ubuntu package)
linux-intel-iot-realtime (Ubuntu package)
linux-gcp-fips (Ubuntu package)
linux-aws-fips (Ubuntu package)
linux-azure-fips (Ubuntu package)
linux-hwe-6.17 (Ubuntu package)
linux-gcp-6.17 (Ubuntu package)
linux-oracle-6.17 (Ubuntu package)
linux-azure-6.17 (Ubuntu package)
linux-oem-6.17 (Ubuntu package)
linux-nvidia-6.17 (Ubuntu package)
linux-aws-6.17 (Ubuntu package)
linux-realtime-6.17 (Ubuntu package)
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-6_4_0-150700_53_55-default-debuginfo
kernel-livepatch-SLE15-SP7_Update_15-debugsource
kernel-livepatch-6_4_0-150700_53_55-default
kernel-debuginfo
kernel-tools
kernel-source
kernel-devel
kernel-debugsource
perf
bpftool-debuginfo
bpftool
kernel
python3-perf-debuginfo
python3-perf
python2-perf-debuginfo
python2-perf
perf-debuginfo
kernel-tools-devel
kernel-tools-debuginfo
kernel-headers
gfs2-kmp-rt-debuginfo
kernel-source-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
gfs2-kmp-rt
kernel-syms-rt
ocfs2-kmp-rt
cluster-md-kmp-rt
kernel-rt-debugsource
kernel-devel-rt
kernel-rt
reiserfs-kmp-default
kernel-azure
kernel-azure-debugsource
kernel-azure-debuginfo
kernel-azure-devel-debuginfo
kernel-azure-devel
kernel-default-extra-debuginfo
kernel-default-extra
kernel-default-livepatch
kernel-default-livepatch-devel
reiserfs-kmp-default-debuginfo
dlm-kmp-default-debuginfo
kernel-default-debugsource
gfs2-kmp-default
gfs2-kmp-default-debuginfo
ocfs2-kmp-default-debuginfo
kernel-default-debuginfo
cluster-md-kmp-default
dlm-kmp-default
cluster-md-kmp-default-debuginfo
ocfs2-kmp-default
kernel-default
kernel-64kb
kernel-64kb-devel-debuginfo
kernel-64kb-debugsource
kernel-64kb-devel
kernel-64kb-debuginfo
kernel-zfcpdump
kernel-macros
kernel-default-devel
kernel-default-devel-debuginfo
kernel-zfcpdump-debuginfo
kernel-zfcpdump-debugsource
kernel-docs
kernel-syms
kernel-obs-build
kernel-obs-build-debugsource
kernel-default-base
linux-aws-hwe (Ubuntu package)
linux-oracle-5.4 (Ubuntu package)
linux-azure-5.4 (Ubuntu package)
linux (Debian package)
linux-hwe-6.8 (Ubuntu package)
linux-aws-6.8 (Ubuntu package)
linux-azure-fde-6.8 (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux-raspi-realtime (Ubuntu package)
linux-azure-fde-6.17 (Ubuntu package)

How to mitigate CVE-2026-31668

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 4.15.0-254.266, 4.15.0-1150.162, 4.15.0-1177.182, 4.15.0-1188.205, 4.15.0-1195.208, 4.15.0-1205.220, 4.15.0-2096.102, 4.15.0-2113.119, 4.15.0-2133.139, 4.15.0.254.238, 4.15.0.1150.147, 4.15.0.1177.168, 4.15.0.1188.201~16.04.1, 4.15.0.1195.193, 4.15.0.1205.173, 4.15.0.2096.94, 4.15.0.2113.109, 4.15.0.2133.127, 5.4.0-234.254~18.04.1, 5.4.0-234.254, 5.4.0-1066.69, 5.4.0-1080.84, 5.4.0-1108.113~18.04.1, 5.4.0-1108.113, 5.4.0-1121.128, 5.4.0-1136.146, 5.4.0-1145.158~18.04.1, 5.4.0-1145.158, 5.4.0-1160.170+fips1, 5.4.0-1162.173~18.04.1, 5.4.0-1162.173, 5.4.0-1165.174~18.04.1, 5.4.0-1165.174, 5.4.0-1167.173, 5.4.0.234.226, 5.4.0.1080.80, 5.4.0.1108.137, 5.4.0.1121.117, 5.4.0.1136.133, 5.4.0.1145.176, 5.4.0.1160.154, 5.4.0.1162.160, 5.4.0.1165.167, 5.4.0.1167.159, 5.15.0-185.195, 6.8.0-134.134, 6.8.0-1057.58~22.04.1, 6.8.0-1058.61~22.04.1, 6.8.0-1058.61+fips1, 6.8.0-1060.61, 6.8.0-1060.63~22.04.1, 6.8.0-1060.63+fips1, 6.8.0-1063.69, 6.8.0-1063.69+fips1, 6.8.1-1055.56~22.04.1, 6.8.1-1055.56, 6.17.0-40.40
linux-kvm (Ubuntu package) - addressed in versions 5.4.0-1149.158, 5.4.0.1149.145, 5.15.0-1103.108
linux-aws (Ubuntu package) - addressed in versions 5.15.0-1111.118, 6.17.0-1019.19
linux-gcp (Ubuntu package) - addressed in versions 5.15.0-1111.121, 6.17.0-1020.22
linux-azure (Ubuntu package) - addressed in versions 4.15.0-1205.220~14.04.1, 5.15.0-1116.125, 6.8.0-1063.71~22.04.1, 6.8.0-1063.71
linux-raspi (Ubuntu package) - addressed in versions 5.15.0-1105.108, 6.8.0-1060.64, 6.17.0-1021.21
linux-oracle (Ubuntu package) - addressed in versions 4.15.0-1158.169~16.04.1, 4.15.0-1158.169, 4.15.0.1158.163, 5.15.0-1108.114, 6.17.0-1018.18
linux-lowlatency (Ubuntu package) - update to 5.15.0-183.193
linux-gke (Ubuntu package) - update to 5.15.0-1107.113
linux-aws-5.15 (Ubuntu package) - update to 5.15.0-1111.118~20.04.1
linux-lowlatency-hwe-5.15 (Ubuntu package) - update to 5.15.0-183.193~20.04.1
linux-hwe-5.15 (Ubuntu package) - update to 5.15.0-185.195~20.04.1
linux-fips (Ubuntu package) - update to 5.15.0-185.195+fips1
linux-azure-5.15 (Ubuntu package) - update to 5.15.0-1116.125~20.04.1
linux-nvidia-tegra (Ubuntu package) - addressed in versions 5.15.0-1063.63, 6.8.0-1029.30
linux-gkeop (Ubuntu package) - update to 5.15.0-1094.102
linux-nvidia-tegra-igx (Ubuntu package) - update to 5.15.0-1052.52
linux-nvidia (Ubuntu package) - update to 5.15.0-1106.107
linux-realtime (Ubuntu package) - addressed in versions 5.15.0-1110.119, 6.17.0-1017.19
linux-intel-iotg (Ubuntu package) - update to 5.15.0-1106.112
linux-azure-fde-5.15 (Ubuntu package) - update to 5.15.0-1116.125~20.04.1
linux-ibm-5.15 (Ubuntu package) - update to 5.15.0-1105.109~20.04.1
linux-ibm (Ubuntu package) - update to 5.15.0-1105.109
linux-intel-iotg-5.15 (Ubuntu package) - update to 5.15.0-1106.112~20.04.1
linux-oracle-5.15 (Ubuntu package) - update to 5.15.0-1108.114~20.04.1
linux-gcp-5.15 (Ubuntu package) - update to 5.15.0-1111.121~20.04.1
linux-nvidia-tegra-5.15 (Ubuntu package) - update to 5.15.0-1063.63~20.04.1
linux-xilinx-zynqmp (Ubuntu package) - update to 5.15.0-1074.78
linux-intel-iot-realtime (Ubuntu package) - update to 5.15.0-1103.105
linux-gcp-fips (Ubuntu package) - addressed in versions 5.4.0-1165.174+fips1, 5.4.0.1165.107, 5.15.0-1111.121+fips1
linux-aws-fips (Ubuntu package) - addressed in versions 5.4.0-1163.174+fips1, 5.4.0.1163.110, 5.15.0-1111.118+fips1
linux-azure-fips (Ubuntu package) - addressed in versions 5.15.0-1116.125+fips1, 6.8.0-134.134+fips1, 6.8.0-1062.69+fips1
linux-hwe-6.17 (Ubuntu package) - update to 6.17.0-40.40~24.04.1
linux-gcp-6.17 (Ubuntu package) - update to 6.17.0-1020.22~24.04.1
linux-oracle-6.17 (Ubuntu package) - update to 6.17.0-1018.18~24.04.1
linux-azure-6.17 (Ubuntu package) - update to 6.17.0-1021.21~24.04.1
linux-oem-6.17 (Ubuntu package) - update to 6.17.0-1028.28
linux-nvidia-6.17 (Ubuntu package) - update to 6.17.0-1026.26
linux-aws-6.17 (Ubuntu package) - update to 6.17.0-1019.19~24.04.1
linux-realtime-6.17 (Ubuntu package) - update to 6.17.0-1017.19~24.04.1
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-6_4_0-150700_53_55-default-debuginfo - update to 1-150700.15.3.1
kernel-livepatch-SLE15-SP7_Update_15-debugsource - update to 1-150700.15.3.1
kernel-livepatch-6_4_0-150700_53_55-default - update to 1-150700.15.3.1
kernel-debuginfo - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
kernel-tools - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
kernel-source - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
kernel-devel - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
kernel-debugsource - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
perf - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
bpftool-debuginfo - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
bpftool - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
kernel - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
python3-perf-debuginfo - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
python3-perf - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
python2-perf-debuginfo - update to 4.19.90-2608.6.0.0388
python2-perf - update to 4.19.90-2608.6.0.0388
perf-debuginfo - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
kernel-tools-devel - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
kernel-tools-debuginfo - addressed in versions 4.19.90-2608.6.0.0388, 5.10.0-316.0.0.219
kernel-headers - update to 5.10.0-316.0.0.219
gfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.54.1
kernel-source-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
gfs2-kmp-rt - update to 6.4.0-150700.7.54.1
kernel-syms-rt - update to 6.4.0-150700.7.54.1
ocfs2-kmp-rt - update to 6.4.0-150700.7.54.1
cluster-md-kmp-rt - update to 6.4.0-150700.7.54.1
kernel-rt-debugsource - update to 6.4.0-150700.7.54.1
kernel-devel-rt - update to 6.4.0-150700.7.54.1
kernel-rt - update to 6.4.0-150700.7.54.1
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-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
reiserfs-kmp-default-debuginfo - update to 6.4.0-150700.53.55.1
kernel-source - 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
ocfs2-kmp-default-debuginfo - update to 6.4.0-150700.53.55.1
kernel-default-debuginfo - update to 6.4.0-150700.53.55.1
cluster-md-kmp-default - 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
ocfs2-kmp-default - update to 6.4.0-150700.53.55.1
kernel-default - update to 6.4.0-150700.53.55.1
kernel-64kb - update to 6.4.0-150700.53.55.1
kernel-64kb-devel-debuginfo - update to 6.4.0-150700.53.55.1
kernel-64kb-debugsource - update to 6.4.0-150700.53.55.1
kernel-64kb-devel - update to 6.4.0-150700.53.55.1
kernel-64kb-debuginfo - update to 6.4.0-150700.53.55.1
kernel-zfcpdump - update to 6.4.0-150700.53.55.1
kernel-macros - update to 6.4.0-150700.53.55.1
kernel-devel - 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-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-obs-build-debugsource - 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
linux-aws-hwe (Ubuntu package) - addressed in versions 4.15.0-254.266~16.04.1, 4.15.0-1188.205~16.04.1, 4.15.0-1195.208~16.04.1, 4.15.0-1205.220~16.04.1
linux-oracle-5.4 (Ubuntu package) - update to 5.4.0-1161.171~18.04.1
linux-azure-5.4 (Ubuntu package) - addressed in versions 5.4.0-1167.173~18.04.1, 5.4.0-1167.173+fips1, 5.4.0.1167.103
linux (Debian package) - addressed in versions 6.1.170-1, 6.12.85-1
linux-hwe-6.8 (Ubuntu package) - update to 6.8.0-136.136~22.04.1
linux-aws-6.8 (Ubuntu package) - addressed in versions 6.8.0-1045.48, 6.8.0-1057.58~22.04.1, 6.8.0-1058.61.1, 6.8.0-1058.64, 6.8.0-1060.61~22.04.1, 6.8.0-1060.63~22.04.1, 6.8.0-1063.69~22.04.1
linux-azure-fde-6.8 (Ubuntu package) - update to 6.8.0-1062.69~22.04.1
linux-azure-fde (Ubuntu package) - update to 6.8.0-1062.69
linux-raspi-realtime (Ubuntu package) - update to 6.8.0-2049.50
linux-azure-fde-6.17 (Ubuntu package) - update to 6.17.0-1018.18~24.04.1

External References

Related Security Bulletins