SB20260727286 - Improper access control in Linux kernel kvm

Description

This security bulletin contains information about 1 vulnerability.

1) Improper access control (CVE-ID: CVE-2026-64285)

CWE-ID: CWE-284 - Improper Access Control

CVSSv4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a local user to corrupt read-only memory.

The vulnerability exists due to improper access control in guest_memfd population for SNP guest CPUID data when populating a guest_memfd instance from a user-supplied source page. A local user can provide CPUID data backed by a read-only mapping to corrupt read-only memory.

Exploitation requires the source page to be used for initial CPUID data for an SNP guest, and well-behaved VMMs are unlikely to be affected because such CPUID data is typically generated dynamically by userspace.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/dcdb476f5fc5701ec06c23efe3e3529f07ca391e
• https://git.kernel.org/stable/c/f13e900599089b10113ceb36013423f0837c6792