NULL pointer dereference in Linux kernel - CVE-2026-89963

Vulnerability identifier: #VU150329

CSH Severity: Low

CVSS v4: 6.7 [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]

CVE-ID: CVE-2026-89963

CWE-ID: CWE-476

Exploitation vector: Local access

Exploit availability: No public exploit available

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

The vulnerability exists due to a null pointer dereference in kexec_extra_fdt_size_ppc64() when calculating extra FDT size during kexec file loading on a platform without reserved memory regions. A local privileged user can invoke kexec file loading to cause a denial of service.

Linux kernel
Debian Linux
Ubuntu
linux (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-ibm (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux (Debian package)

Install security update from vendor's repository.

linux (Ubuntu package) - update to 7.0.0-42.42
linux-aws (Ubuntu package) - update to 7.0.0-1016.17
linux-gcp (Ubuntu package) - update to 7.0.0-1016.18
linux-oracle (Ubuntu package) - update to 7.0.0-1015.16
linux-ibm (Ubuntu package) - update to 7.0.0-1017.17
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-42.42~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1017.17
linux (Debian package) - update to 6.12.111-1

• https://git.kernel.org/stable/c/11ef1c2a5dbe0bd8c1345f59bab7331d352f02cf
• https://git.kernel.org/stable/c/4ff3d9fd71c7bc2fc81afdac1970d9c55a5c0dea
• https://git.kernel.org/stable/c/761eda315a6e1fda3e8e2185b28430771fb1ac29
• https://git.kernel.org/stable/c/df45337587db21c502fe5251d3bcc7887428f4fb

• NULL pointer dereference in Linux kernel powerpc kexec
• Debian update for linux
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more