NULL pointer dereference in Linux kernel - CVE-2026-99093

Vulnerability identifier: #VU157694

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-2026-99093

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 by triggering a kernel panic during boot.

The vulnerability exists due to a null pointer dereference in pagetable_free_kernel() when boot-time function tracing triggers deferred kernel page table freeing before workqueue initialization. A local privileged user can configure boot-time tracing with ftrace=function ftrace_filter=pud_free_pmd_page to trigger work submission through the still-null system_percpu_wq pointer and cause a kernel panic.

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

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - update to 7.0.0-43.43
linux-gcp (Ubuntu package) - update to 7.0.0-1017.19
linux-aws (Ubuntu package) - update to 7.0.0-1017.18
linux-oracle (Ubuntu package) - update to 7.0.0-1016.18
linux-azure (Ubuntu package) - update to 7.0.0-1020.21
linux-ibm (Ubuntu package) - update to 7.0.0-1018.18
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1018.18

• https://git.kernel.org/stable/c/2fb552b0bee70c24c092720028ab4620f5eb2646
• https://git.kernel.org/stable/c/7a25ca170c12a9328f6fcf4410713beb516b01c0
• https://git.kernel.org/stable/c/df6c704a08bc0925d5db047b0a6221f962bda4d9

• NULL pointer dereference in Linux kernel mm
• Ubuntu update for linux, linux-aws, linux-gcp and more
• Ubuntu update for linux-azure