{"id":"CVE-2026-23401","summary":"KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE","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's 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 ]---","modified":"2026-04-19T04:18:03.259154Z","published":"2026-04-01T08:36:32.367Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23401.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/20656cd1f243d3a154aac5dd1b823110b6906fe1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/459158151a158a6703b49f3c9de0e536d8bd553f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/695320de6eadb75aaed8be1787c4ce4c189e4c7b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aad885e774966e97b675dfe928da164214a71605"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bce7fe59d43531623f3e43779127bfb33804925d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ed5909992f344a7d3f4024261e9f751d9618a27d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fd28c5618699180cd69619801e9ae6a5266c0a22"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23401.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23401"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"a54aa15c6bda3ca7e2f9e040ba968a1da303e24f"},{"fixed":"20656cd1f243d3a154aac5dd1b823110b6906fe1"},{"fixed":"ed5909992f344a7d3f4024261e9f751d9618a27d"},{"fixed":"fd28c5618699180cd69619801e9ae6a5266c0a22"},{"fixed":"459158151a158a6703b49f3c9de0e536d8bd553f"},{"fixed":"695320de6eadb75aaed8be1787c4ce4c189e4c7b"},{"fixed":"bce7fe59d43531623f3e43779127bfb33804925d"},{"fixed":"aad885e774966e97b675dfe928da164214a71605"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23401.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.13.0"},{"fixed":"5.15.203"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.168"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.131"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.80"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.21"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23401.json"}}],"schema_version":"1.7.5"}