SB20260425125 - Improper Validation of Specified Quantity in Input in Linux kernel kvm svm

Description

This security bulletin contains information about 1 vulnerability.

1) Improper Validation of Specified Quantity in Input (CVE-ID: CVE-2026-31593)

CWE-ID: CWE-1284 - Improper Validation of Specified Quantity in Input

CVSSv4: 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]

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to improper state validation in the KVM SEV VMSA synchronization logic when synchronizing vCPU state to an already-launched and encrypted vCPU. A local user can issue a crafted ioctl sequence to cause a denial of service.

On hosts with SNP enabled, accessing guest-private memory triggers an RMP page fault that panics the host. In SEV-ES environments without SNP, the issue may clobber guest state instead of panicking the host.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/692fdf05e55fa03960a1278afdc2478c12daea13
• https://git.kernel.org/stable/c/6ef109e01e1d35199e1a97ea68bdfd3cf3fbf9ab
• https://git.kernel.org/stable/c/8f85a4885eee8cb495961ffa371a91828afb9445
• https://git.kernel.org/stable/c/c9609847ae65ca36233077c2b6cb2bc0fb37c77a