Use-after-free in Linux kernel - CVE-2026-45837

Vulnerability identifier: #VU132653

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-2026-45837

CWE-ID: CWE-416

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 use-after-free in arena_vm_close and bpf_arena_free_pages when handling inherited arena VMAs after a fork. A local user can trigger a stale VMA reference by calling bpf_arena_free_pages() in a child process after the parent unmaps the arena to cause a denial of service.

The issue occurs when an arena VMA is inherited across fork and the child retains a pointer to the parent VMA.

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

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 7.0.0-28.28, 7.0.0-28.28.1, 7.0.0-1003.4, 7.0.0-1008.8
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1009.9
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15

• https://git.kernel.org/stable/c/201128fcc7b213d27ab77bc4e89488b41796480f
• https://git.kernel.org/stable/c/4fddde2a732de60bb97e3307d4eb69ac5f1d2b74
• https://git.kernel.org/stable/c/723b9fa930cc277c15ce6b9ec9feec828cfac9d7
• https://git.kernel.org/stable/c/d18099f19e53250f8ad2801498b88cec29d9107a

• Use-after-free in Linux kernel bpf
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws