---
id: CVE-2026-89908
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  LoongArch: KVM: Preserve memslot arch flags on KVM_MR_FLAGS_ONLY

  kvm_arch_prepare_memory_region() computes new->arch.flags, i.e
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  LoongArch: KVM: Preserve memslot arch flags on KVM_MR_FLAGS_ONLY

  kvm_arch_prepare_memory_region() computes new->arch.flags, i.e. whether
  a memslot is KVM_MEM_HUGEPAGE_…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c <
    7c6df65b53846cd7a9a1c81c6ddb42fdc08603e8
  - >-
    Linux >= 7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c <
    4e4dbc341b1581dc512b85d98b768373b0398366
  - >-
    Linux >= 7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c <
    bc7a6849b4395f45a602db91b0fb2fb2e9ed4bba
  - >-
    Linux >= 7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c <
    27a9bfee3bbcb3cabb77797354f07e0e44e49831
  - Linux 6.8
published: '2026-09-16'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T15:18:17.050'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89908'
references:
  - url: 'https://git.kernel.org/stable/c/27a9bfee3bbcb3cabb77797354f07e0e44e49831'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4e4dbc341b1581dc512b85d98b768373b0398366'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7c6df65b53846cd7a9a1c81c6ddb42fdc08603e8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/bc7a6849b4395f45a602db91b0fb2fb2e9ed4bba'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-16T10:53:53.976Z'
epss: 0.00163
epssPercentile: 0.05975
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

LoongArch: KVM: Preserve memslot arch flags on KVM_MR_FLAGS_ONLY

kvm_arch_prepare_memory_region() computes new->arch.flags, i.e. whether
a memslot is KVM_MEM_HUGEPAGE_CAPABLE or KVM_MEM_HUGEPAGE_INCAPABLE,
only for KVM_MR_CREATE and KVM_MR_MOVE, and returns early for every
other change. But the generic code allocates a zeroed memslot for every
change and never copies old->arch, so after a KVM_MR_FLAGS_ONLY update,
e.g. toggling KVM_MEM_LOG_DIRTY_PAGES for live migration, the active
memslot has arch.flags == 0.

With both flags clear, fault_supports_huge_mapping() falls through to
the alignment check on the HVA range alone, which no longer verifies
that the GPA and HVA have the same offset within a PMD. A memslot that
was marked KVM_MEM_HUGEPAGE_INCAPABLE because of a GPA/HVA offset
mismatch can then be mapped with PMD entries on read faults, and since
kvm_map_page() aligns the gfn and the pfn independently, the guest ends
up accessing the wrong host pages, exactly the "d -> f, e -> g" case
described in the comment above the check.

Carry the arch flags over from the old memslot for KVM_MR_FLAGS_ONLY,
as the GPA, HVA and size are guaranteed to be unchanged for that case.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.