GHSA-2G4M-3WVW-CRQ2
Vulnerability from github – Published: 2026-04-01 09:31 – Updated: 2026-07-08 15:31In 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: 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 ---[ end trace 0000000000000000 ]---
{
"affected": [],
"aliases": [
"CVE-2026-23401"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-04-01T09:16:15Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE\n\nWhen installing an emulated MMIO SPTE, do so *after* dropping/zapping the\nexisting SPTE (if it\u0027s shadow-present). While commit a54aa15c6bda3 was\nright about it being impossible to convert a shadow-present SPTE to an\nMMIO SPTE due to a _guest_ write, it failed to account for writes to guest\nmemory that are outside the scope of KVM.\n\nE.g. if host userspace modifies a shadowed gPTE to switch from a memslot\nto emulted MMIO and then the guest hits a relevant page fault, KVM will\ninstall the MMIO SPTE without first zapping the shadow-present SPTE.\n\n ------------[ cut here ]------------\n is_shadow_present_pte(*sptep)\n WARNING: arch/x86/kvm/mmu/mmu.c:484 at mark_mmio_spte+0xb2/0xc0 [kvm], CPU#0: vmx_ept_stale_r/4292\n Modules linked in: kvm_intel kvm irqbypass\n CPU: 0 UID: 1000 PID: 4292 Comm: vmx_ept_stale_r Not tainted 7.0.0-rc2-eafebd2d2ab0-sink-vm #319 PREEMPT\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n RIP: 0010:mark_mmio_spte+0xb2/0xc0 [kvm]\n Call Trace:\n \u003cTASK\u003e\n mmu_set_spte+0x237/0x440 [kvm]\n ept_page_fault+0x535/0x7f0 [kvm]\n kvm_mmu_do_page_fault+0xee/0x1f0 [kvm]\n kvm_mmu_page_fault+0x8d/0x620 [kvm]\n vmx_handle_exit+0x18c/0x5a0 [kvm_intel]\n kvm_arch_vcpu_ioctl_run+0xc55/0x1c20 [kvm]\n kvm_vcpu_ioctl+0x2d5/0x980 [kvm]\n __x64_sys_ioctl+0x8a/0xd0\n do_syscall_64+0xb5/0x730\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n RIP: 0033:0x47fa3f\n \u003c/TASK\u003e\n ---[ end trace 0000000000000000 ]---",
"id": "GHSA-2g4m-3wvw-crq2",
"modified": "2026-07-08T15:31:27Z",
"published": "2026-04-01T09:31:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23401"
},
{
"type": "WEB",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23401.json"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fd28c5618699180cd69619801e9ae6a5266c0a22"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ed5909992f344a7d3f4024261e9f751d9618a27d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bce7fe59d43531623f3e43779127bfb33804925d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/aad885e774966e97b675dfe928da164214a71605"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/695320de6eadb75aaed8be1787c4ce4c189e4c7b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/459158151a158a6703b49f3c9de0e536d8bd553f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/20656cd1f243d3a154aac5dd1b823110b6906fe1"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2453803"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2026-23401"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:36534"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:36533"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:36532"
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{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:36531"
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{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:36530"
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{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:20593"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:19875"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:19569"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:19568"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:19521"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:15883"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:14339"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:14230"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:14137"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:13936"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:13932"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:13578"
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{
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"url": "https://access.redhat.com/errata/RHSA-2026:13577"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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