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CVE-2026-23401— KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于安装模拟MMIO SPTE时未先删除现有SPTE，可能导致内存损坏。

AI Predicted 4.7 Difficulty: Easy EPSS 0.18% · P8

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux a54aa15c6bda3ca7e2f9e040ba968a1da303e24f< 20656cd1f243d3a154aac5dd1b823110b6906fe1 affected
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f< ed5909992f344a7d3f4024261e9f751d9618a27d affected
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f< fd28c5618699180cd69619801e9ae6a5266c0a22 affected
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f< 459158151a158a6703b49f3c9de0e536d8bd553f affected
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f< 695320de6eadb75aaed8be1787c4ce4c189e4c7b affected
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f< bce7fe59d43531623f3e43779127bfb33804925d affected
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f< aad885e774966e97b675dfe928da164214a71605 affected
5.13 affected
… +8 more rows
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I. Basic Information for CVE-2026-23401

Vulnerability Information
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Vulnerability Title
KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE When installing an emulated MMIO SPTE, do so *after* dropping/zapping the existing SPTE (if it's shadow-present). While commit a54aa15c6bda3 was right about it being impossible to convert a shadow-present SPTE to an MMIO SPTE due to a _guest_ write, it failed to account for writes to guest memory that are outside the scope of KVM. E.g. if host userspace modifies a shadowed gPTE to switch from a memslot to emulted MMIO and then the guest hits a relevant page fault, KVM will install the MMIO SPTE without first zapping the shadow-present SPTE. ------------[ cut here ]------------ is_shadow_present_pte(*sptep) WARNING: arch/x86/kvm/mmu/mmu.c:484 at mark_mmio_spte+0xb2/0xc0 [kvm], CPU#0: vmx_ept_stale_r/4292 Modules linked in: kvm_intel kvm irqbypass CPU: 0 UID: 1000 PID: 4292 Comm: vmx_ept_stale_r Not tainted 7.0.0-rc2-eafebd2d2ab0-sink-vm #319 PREEMPT Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:mark_mmio_spte+0xb2/0xc0 [kvm] Call Trace: <TASK> mmu_set_spte+0x237/0x440 [kvm] ept_page_fault+0x535/0x7f0 [kvm] kvm_mmu_do_page_fault+0xee/0x1f0 [kvm] kvm_mmu_page_fault+0x8d/0x620 [kvm] vmx_handle_exit+0x18c/0x5a0 [kvm_intel] kvm_arch_vcpu_ioctl_run+0xc55/0x1c20 [kvm] kvm_vcpu_ioctl+0x2d5/0x980 [kvm] __x64_sys_ioctl+0x8a/0xd0 do_syscall_64+0xb5/0x730 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x47fa3f </TASK> ---[ end trace 0000000000000000 ]---
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于安装模拟MMIO SPTE时未先删除现有SPTE，可能导致内存损坏。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux a54aa15c6bda3ca7e2f9e040ba968a1da303e24f ~ 20656cd1f243d3a154aac5dd1b823110b6906fe1 -
Linux Linux 5.13 -

II. Public POCs for CVE-2026-23401

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III. Intelligence Information for CVE-2026-23401

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Patches & Fixes for CVE-2026-23401 (1)

Same Patch Batch · Linux · 2026-04-01 · 11 CVEs total

CVE-2026-23411 7.8 HIGH apparmor: fix race between freeing data and fs accessing it
CVE-2026-23410 7.8 HIGH apparmor: fix race on rawdata dereference
CVE-2026-23408 7.8 HIGH apparmor: Fix double free of ns_name in aa_replace_profiles()
CVE-2026-23407 7.8 HIGH apparmor: fix missing bounds check on DEFAULT table in verify_dfa()
CVE-2026-23406 7.8 HIGH apparmor: fix side-effect bug in match_char() macro usage
CVE-2026-23409 apparmor: fix differential encoding verification
CVE-2026-23405 apparmor: fix: limit the number of levels of policy namespaces
CVE-2026-23404 apparmor: replace recursive profile removal with iterative approach
CVE-2026-23403 apparmor: fix memory leak in verify_header
CVE-2026-23402 KVM: x86/mmu: Only WARN in direct MMUs when overwriting shadow-present SPTE

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23401

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