Improper locking in Linux kernel - CVE-2026-31591

Vulnerability identifier: #VU127805

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-2026-31591

CWE-ID: CWE-667

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 improper locking in KVM SEV VMSA synchronization for SNP launch finish when synchronizing and encrypting VMSAs for SNP guests. A local user can manipulate or run a vCPU during synchronization to cause a denial of service.

The issue can corrupt vCPU state and may crash the host kernel.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-realtime (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-aws (Ubuntu package)
linux-raspi (Ubuntu package)
linux-azure (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-ibm (Ubuntu package)
linux-azure-fde (Ubuntu package)

Install security update from vendor's repository.

linux (Ubuntu package) - update to 7.0.0-27.27
linux-realtime (Ubuntu package) - update to 7.0.0-27.27.1
linux-gcp (Ubuntu package) - update to 7.0.0-1007.7
linux-oracle (Ubuntu package) - update to 7.0.0-1007.7
linux-aws (Ubuntu package) - update to 7.0.0-1008.8
linux-raspi (Ubuntu package) - update to 7.0.0-1014.14
linux-azure (Ubuntu package) - update to 7.0.0-1010.10
linux-nvidia (Ubuntu package) - update to 7.0.0-1013.13
linux-ibm (Ubuntu package) - update to 7.0.0-1009.9
linux-azure-fde (Ubuntu package) - update to 7.0.0-1009.9

• https://git.kernel.org/stable/c/30fd9d8c82087742168db779929d8be0459b0716
• https://git.kernel.org/stable/c/4df77742e8b9a6b935bdf46f02fd0aca4d4ee7f5
• https://git.kernel.org/stable/c/c87938fc7d99a06a7e5477c45b4e5a4148f85d66

• Improper locking in Linux kernel kvm svm
• Ubuntu update for linux
• Ubuntu update for linux-raspi
• Ubuntu update for linux-nvidia
• Ubuntu update for linux-azure