Use-after-free in Linux kernel - CVE-2026-98440

Vulnerability identifier: #VU156738

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-2026-98440

CWE-ID: CWE-416

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to potentially cause a denial of service through access to freed kernel memory.

The vulnerability exists due to use-after-free in the Linux kernel arm64 KVM nested virtualization subsystem when kvm_arch_flush_shadow_all() frees shadow stage-2 MMU containers that other parts of the system may still reference. A local user can potentially trigger access to these freed structures during shadow mapping operations to cause a kernel crash.

Linux kernel
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)

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

• https://git.kernel.org/stable/c/22e82acec93a681071ed36f70eabe2d0c4e0bebd
• https://git.kernel.org/stable/c/5bf1c9175e657b3c2dc1cf77403031ac7aadcf66
• https://git.kernel.org/stable/c/876049f026b4dfaca0cc78ec81be0e639ca8525d
• https://git.kernel.org/stable/c/e5843f4effaa2ffac3e789ecd4456403564961d4

• Use-after-free in Linux kernel arm64 kvm
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more