Out-of-bounds read in Linux kernel - CVE-2026-31709

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Main Vulnerability Database Vulnerabilities #VU128994

Out-of-bounds read in Linux kernel - CVE-2026-31709

Published: May 2, 2026


Vulnerability identifier: #VU128994
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-31709
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to an out-of-bounds read in cifsacl DACL rewrite helpers when processing a server-supplied truncated DACL. A remote attacker can send a malformed ACL response to cause a denial of service.

The issue occurs because the incoming DACL body and each ACE were not structurally validated before chmod/chown security descriptor rebuild paths walked the ACE list.


Affected software

Linux kernel
Debian Linux
SUSE Linux Micro Extras
SUSE Linux Micro
Red Hat Enterprise Linux for x86_64
Anolis OS
Red Hat Enterprise Linux for Real Time for NFV
Red Hat Enterprise Linux for Real Time
Red Hat CodeReady Linux Builder for Power, little endian
Red Hat CodeReady Linux Builder for ARM 64
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
Red Hat CodeReady Linux Builder for x86_64
Red Hat Enterprise Linux Server - AUS
Ubuntu
openEuler
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
linux (Ubuntu package)
linux-kvm (Ubuntu package)
linux-gcp (Ubuntu package)
linux-aws (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-azure-fde-5.15 (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-realtime (Ubuntu package)
linux-intel-iotg (Ubuntu package)
linux-nvidia-tegra-igx (Ubuntu package)
linux-gkeop (Ubuntu package)
linux-nvidia-tegra (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-azure-fde (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)
kernel (Red Hat package)
kernel-rt (Red Hat package)
kernel-doc
kernel-abi-stablelists
python3-perf
perf
kernel-tools-libs-devel
kernel-tools-libs
kernel-tools
kernel-modules-extra
kernel-modules
kernel-headers
kernel-devel
bpftool
kernel-debug-modules-extra
kernel
kernel-core
kernel-cross-headers
kernel-debug
kernel-debug-core
kernel-debug-devel
kernel-debug-modules
kernel-default-devel
kernel-default-devel-debuginfo
kernel-default-debugsource
kernel-obs-build-debugsource
kernel-obs-build
kernel-syms
kernel-64kb-devel
kernel-64kb-debugsource
kernel-64kb
kernel-default
python3-perf-debuginfo
perf-debuginfo
kernel-tools-devel
kernel-tools-debuginfo
kernel-source
kernel-debugsource
bpftool-debuginfo
kernel-debuginfo
kernel-extra-modules
linux-hwe-6.8 (Ubuntu package)
linux-oracle-6.8 (Ubuntu package)
linux-aws-6.8 (Ubuntu package)
linux-azure-fde-6.8 (Ubuntu package)
linux (Debian package)

How to mitigate CVE-2026-31709

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 5.15.0-198.208, 6.8.0-136.136, 6.8.0-1046.50, 6.8.0-1059.67, 6.8.0-1064.72~22.04.1, 6.8.0-1064.72, 6.8.1-1056.57~22.04.2, 6.8.1-1056.57, 7.0.0-27.27
linux-kvm (Ubuntu package) - update to 5.15.0-1109.114
linux-gcp (Ubuntu package) - addressed in versions 5.15.0-1118.128, 7.0.0-1007.7
linux-aws (Ubuntu package) - addressed in versions 5.15.0-1117.124, 6.8.0-1061.64+1, 7.0.0-1008.8
linux-azure (Ubuntu package) - addressed in versions 5.15.0-1123.132, 6.8.0-1063.71~22.04.1, 6.8.0-1063.71, 7.0.0-1010.10
linux-raspi (Ubuntu package) - addressed in versions 5.15.0-1113.116, 6.8.0-1061.65, 6.8.0-2050.52, 7.0.0-1014.14
linux-oracle (Ubuntu package) - addressed in versions 5.15.0-1114.120, 7.0.0-1007.7
linux-lowlatency (Ubuntu package) - update to 5.15.0-195.205
linux-gke (Ubuntu package) - update to 5.15.0-1113.119
linux-aws-5.15 (Ubuntu package) - update to 5.15.0-1117.124~20.04.1
linux-lowlatency-hwe-5.15 (Ubuntu package) - update to 5.15.0-195.205~20.04.1
linux-hwe-5.15 (Ubuntu package) - update to 5.15.0-198.208~20.04.1
linux-fips (Ubuntu package) - addressed in versions 5.15.0-198.208+fips1, 6.8.0-136.136+fips2, 6.8.0-136.136.2~22.04.1, 6.8.0-136.136.2, 6.8.0-1058.61
linux-azure-5.15 (Ubuntu package) - update to 5.15.0-1123.132~20.04.1
linux-azure-fde-5.15 (Ubuntu package) - update to 5.15.0-1122.131~20.04.1
linux-nvidia (Ubuntu package) - addressed in versions 5.15.0-1112.113, 6.8.0-1059.62~22.04.1, 6.8.0-1059.62, 6.8.0-1059.62.1, 7.0.0-1013.13
linux-realtime (Ubuntu package) - addressed in versions 5.15.0-1116.125, 7.0.0-27.27.1
linux-intel-iotg (Ubuntu package) - update to 5.15.0-1112.118
linux-nvidia-tegra-igx (Ubuntu package) - update to 5.15.0-1059.59
linux-gkeop (Ubuntu package) - update to 5.15.0-1100.108
linux-nvidia-tegra (Ubuntu package) - update to 5.15.0-1070.72
linux-ibm-5.15 (Ubuntu package) - update to 5.15.0-1111.115~20.04.1
linux-ibm (Ubuntu package) - addressed in versions 5.15.0-1111.115, 6.8.0-1030.31, 6.8.0-1033.34, 6.8.0-1061.62~22.04.1, 6.8.0-1061.62, 7.0.0-1009.9
linux-intel-iotg-5.15 (Ubuntu package) - update to 5.15.0-1112.118~20.04.1
linux-oracle-5.15 (Ubuntu package) - update to 5.15.0-1114.120~20.04.1
linux-gcp-5.15 (Ubuntu package) - update to 5.15.0-1118.128~20.04.1
linux-nvidia-tegra-5.15 (Ubuntu package) - update to 5.15.0-1070.72~20.04.1
linux-azure-fde (Ubuntu package) - addressed in versions 5.15.0-1122.131, 6.8.0-1062.69, 7.0.0-1009.9
linux-xilinx-zynqmp (Ubuntu package) - update to 5.15.0-1080.84
linux-intel-iot-realtime (Ubuntu package) - update to 5.15.0-1109.111
linux-gcp-fips (Ubuntu package) - addressed in versions 5.15.0-1118.128+fips1, 6.8.0-1064.72+fips1
linux-aws-fips (Ubuntu package) - update to 5.15.0-1117.124+fips1
linux-azure-fips (Ubuntu package) - addressed in versions 5.15.0-1123.132+fips1, 6.8.0-1063.71+fips2
kernel (Red Hat package) - addressed in versions 4.18.0-553.126.1.el8_10, 5.14.0-284.174.1.el9_2, 6.12.0-211.20.1.el10_2
kernel-rt (Red Hat package) - addressed in versions 4.18.0-553.126.1.rt7.467.el8_10, 5.14.0-284.174.1.rt14.459.el9_2
kernel-doc - update to 4.18.0-553.126.1.0.1
kernel-abi-stablelists - update to 4.18.0-553.126.1.0.1
python3-perf - update to 4.18.0-553.126.1.0.1
perf - update to 4.18.0-553.126.1.0.1
kernel-tools-libs-devel - update to 4.18.0-553.126.1.0.1
kernel-tools-libs - update to 4.18.0-553.126.1.0.1
kernel-tools - update to 4.18.0-553.126.1.0.1
kernel-modules-extra - update to 4.18.0-553.126.1.0.1
kernel-modules - update to 4.18.0-553.126.1.0.1
kernel-headers - update to 4.18.0-553.126.1.0.1
kernel-devel - update to 4.18.0-553.126.1.0.1
bpftool - update to 4.18.0-553.126.1.0.1
kernel-debug-modules-extra - update to 4.18.0-553.126.1.0.1
kernel - update to 4.18.0-553.126.1.0.1
kernel-core - update to 4.18.0-553.126.1.0.1
kernel-cross-headers - update to 4.18.0-553.126.1.0.1
kernel-debug - update to 4.18.0-553.126.1.0.1
kernel-debug-core - update to 4.18.0-553.126.1.0.1
kernel-debug-devel - update to 4.18.0-553.126.1.0.1
kernel-debug-modules - update to 4.18.0-553.126.1.0.1
kernel-default-devel - update to 6.4.0-159998.55.1
kernel-default-devel-debuginfo - update to 6.4.0-159998.55.1
kernel-default-debugsource - update to 6.4.0-159998.55.1
kernel-obs-build-debugsource - update to 6.4.0-159998.55.1
kernel-obs-build - update to 6.4.0-159998.55.1
kernel-syms - update to 6.4.0-159998.55.1
kernel-64kb-devel - update to 6.4.0-159998.55.1
kernel-64kb-debugsource - update to 6.4.0-159998.55.1
kernel-64kb - update to 6.4.0-159998.55.1
kernel-default - update to 6.4.0-159998.55.1
kernel - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
python3-perf-debuginfo - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
python3-perf - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
perf-debuginfo - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
perf - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
kernel-tools-devel - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
kernel-tools-debuginfo - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
kernel-tools - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
kernel-source - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
kernel-headers - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
kernel-devel - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
kernel-debugsource - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
bpftool-debuginfo - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
bpftool - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
kernel-debuginfo - addressed in versions 6.6.0-145.1.15.153, 6.6.0-145.3.15.146
kernel-extra-modules - update to 6.6.0-145.3.15.146
linux-hwe-6.8 (Ubuntu package) - update to 6.8.0-136.136~22.04.1
linux-oracle-6.8 (Ubuntu package) - update to 6.8.0-1058.61~22.04.1
linux-aws-6.8 (Ubuntu package) - addressed in versions 6.8.0-1061.64~22.04.1, 6.8.0-1061.64+fips1
linux-azure-fde-6.8 (Ubuntu package) - update to 6.8.0-1062.69~22.04.1
linux (Debian package) - update to 6.12.86-1

External References

Related Security Bulletins