Improper handling of exceptional conditions in Linux kernel - CVE-2026-98653

Vulnerability identifier: #VU156966

CSH Severity: Low

CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98653

CWE-ID: CWE-755

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to potentially cause a denial of service affecting nested guest execution.

The vulnerability exists due to improper handling of missing memory mappings in the Linux kernel's s390 KVM shadow fault handling when shadowing nested guest memory that is not present in the parent guest gmap. A local user can trigger this condition through nested guest memory accesses to cause an unexpected -ENOENT error to propagate to userspace, potentially disrupting nested guest execution.

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/94c43c7df46433ed4d1e18f13770b019ba977bd8
• https://git.kernel.org/stable/c/faff4c8ff3dbec6d71b89dd281a0d17c4478fa44

• Improper handling of exceptional conditions in Linux kernel kvm s390
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more