NULL pointer dereference in Linux kernel - CVE-2026-89835

Vulnerability identifier: #VU150447

CSH Severity: Low

CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-89835

CWE-ID: CWE-476

Exploitation vector: Local access

Exploit availability: No public exploit available

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

The vulnerability exists due to a null pointer dereference in the f2fs ckpt_thread_ioprio sysfs store path when writing the checkpoint thread I/O priority through sysfs while checkpoint merge is enabled and no checkpoint thread is running. A local user can write a checkpoint thread I/O priority value through sysfs to cause a denial of service.

A read-only mount is one condition in which no checkpoint merge thread is started.

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 kernel - update to 7.0 rc3
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/5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f
• https://git.kernel.org/stable/c/8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b
• https://git.kernel.org/stable/c/a6573f3ffc19542de9ebc1a2b1f930fd48ba538c
• https://git.kernel.org/stable/c/aefcec3bebdeed2bff444378122300763325ba23

• NULL pointer dereference in Linux kernel f2fs
• Debian update for linux
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more