NULL pointer dereference in Linux kernel - CVE-2026-23439

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Main Vulnerability Database Vulnerabilities #VU124936

NULL pointer dereference in Linux kernel - CVE-2026-23439

Published: April 6, 2026


Vulnerability identifier: #VU124936
CSH Severity: Low
CVSS v4 BT: 4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]
CVE-ID: CVE-2026-23439
CWE-ID: CWE-476
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local privileged user to cause a denial of service.

The vulnerability exists due to a null pointer dereference in udp_sock_create6() and its caller fou_create() when handling netlink requests with CONFIG_IPV6 disabled. A local privileged user can send a specially crafted netlink request to cause a denial of service.

Only privileged users can trigger the issue, and exploitation requires a kernel built with CONFIG_IPV6 disabled.


Affected software

Linux kernel
Debian Linux
Ubuntu
openEuler
linux (Ubuntu package)
linux-aws (Ubuntu package)
linux-nvidia-tegra (Ubuntu package)
linux-nvidia-tegra-5.15 (Ubuntu package)
linux-ibm-5.15 (Ubuntu package)
linux-azure (Ubuntu package)
linux-azure-5.15 (Ubuntu package)
linux-azure-fips (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux (Debian package)
kernel
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-tools
kernel-source
kernel-headers
kernel-devel
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo
bpftool
kernel-extra-modules
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-azure-fde-6.8 (Ubuntu package)
linux-gcp-fips (Ubuntu package)

How to mitigate CVE-2026-23439

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 5.15.0.184.155, 5.15.0-184.194, 5.15.0-184.194~20.04.1, 5.15.0.186.166, 5.15.0-186.196, 5.15.0-186.196~20.04.1, 5.15.0.1075.78, 5.15.0-1075.79, 5.15.0.1095.94, 5.15.0-1095.103, 5.15.0.1104.100, 5.15.0-1104.109, 5.15.0.1108.107, 5.15.0-1108.114, 5.15.0.1111.115, 5.15.0-1111.120+fips1, 5.15.0.1112.102, 5.15.0.1112.109, 5.15.0-1112.122, 5.15.0-1112.122+fips1, 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-aws (Ubuntu package) - addressed in versions 5.15.0.186.109, 5.15.0-186.196+fips1, 5.15.0.1106.103, 5.15.0-1106.110, 5.15.0.1107.107, 5.15.0-1107.108, 5.15.0.1112.108, 5.15.0.1112.115, 5.15.0-1112.119, 5.15.0-1112.119+fips1, 5.15.0-1112.119~20.04.1, 6.8.0-1061.64+1
linux-nvidia-tegra (Ubuntu package) - addressed in versions 5.15.0-1053.53, 5.15.0.1053.55, 5.15.0.1064.64, 5.15.0-1064.66
linux-nvidia-tegra-5.15 (Ubuntu package) - update to 5.15.0-1064.66~20.04.1
linux-ibm-5.15 (Ubuntu package) - update to 5.15.0-1106.110~20.04.1
linux-azure (Ubuntu package) - addressed in versions 5.15.0.1109.105, 5.15.0-1109.115, 5.15.0.1117.115, 5.15.0-1117.126, 6.8.0-1063.71, 6.8.0-1063.71~22.04.1
linux-azure-5.15 (Ubuntu package) - addressed in versions 5.15.0-1109.115~20.04.1, 5.15.0-1117.126~20.04.1, 5.15.0-1117.126~20.04.2
linux-azure-fips (Ubuntu package) - addressed in versions 5.15.0.1117.102, 5.15.0-1117.126+fips1, 6.8.0-1063.71+fips2
linux-azure-fde (Ubuntu package) - addressed in versions 5.15.0-1117.126, 6.8.0-1062.69
linux (Debian package) - addressed in versions 6.1.170-1, 6.12.85-1
kernel - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
python3-perf-debuginfo - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
python3-perf - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
perf-debuginfo - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
perf - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
kernel-tools-devel - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
kernel-tools-debuginfo - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
kernel-tools - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
kernel-source - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
kernel-headers - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
kernel-devel - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
kernel-debugsource - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
kernel-debuginfo - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
bpftool-debuginfo - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
bpftool - addressed in versions 6.6.0-145.0.4.132, 6.6.0-145.0.4.144, 6.6.0-145.3.14.145
kernel-extra-modules - update to 6.6.0-145.3.14.145
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-azure-fde-6.8 (Ubuntu package) - update to 6.8.0-1062.69~22.04.1
linux-gcp-fips (Ubuntu package) - update to 6.8.0-1064.72+fips1

External References

Related Security Bulletins