Improper access control in Linux kernel - CVE-2026-63941
Published: July 20, 2026
Vulnerability identifier: #VU138711
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-63941
CWE-ID: CWE-284
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to bypass intended vector length restrictions for a nested guest.
The vulnerability exists due to improper access control in the KVM arm64 nested virtualization SVE register handling for ZCR_EL2 when restoring SVE context for an L2 guest after handling guest hypervisor updates through ZCR_EL1. A local user can write an uncapped ZCR_EL2 value via ZCR_EL1 to bypass intended vector length restrictions for a nested guest.
The issue affects VHE guest hypervisor scenarios in nested virtualization on arm64 systems with SVE enabled.
How to mitigate CVE-2026-63941
Install security update from vendor's repository.