{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98717", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.366Z", "datePublished": "2026-10-18T15:46:51.862Z", "dateUpdated": "2026-10-21T12:56:02.536Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:56:02.536Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86/mmu: Bail from shadow walks if the root is invalid or a dummy\n\nWhen walking shadow page tables, immediately terminate the walk if the root\nis a \"dummy\" root, i.e. a root whose top-level page table is backed by the\nzero page, but otherwise doesn't exist. If memslot creation races with a\nstage-2 page fault (EPT violation or #NPF) from L2, then if the stars align,\nKVM will attempt to walk shadow page tables using the zero page and hit a\nNULL pointer deref.\n\n BUG: kernel NULL pointer dereference, address: 0000000000000021\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n PGD 0 P4D 0\n Oops: Oops: 0000 [#1] SMP\n CPU: 30 UID: 1000 PID: 941 Comm: qemu Not tainted 7.2.0-rc2-1b731e5ded48-next-vm #1741 PREEMPTLAZY\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n RIP: 0010:__kvm_mmu_invalidate_addr+0xea/0x210 [kvm]\n Call Trace:\n \n kvm_mmu_invalidate_addr+0x92/0xe0 [kvm]\n __kvm_inject_emulated_page_fault+0x67/0x80 [kvm]\n ept_page_fault+0x160/0x850 [kvm]\n kvm_mmu_do_page_fault+0x102/0x1f0 [kvm]\n kvm_mmu_page_fault+0x8e/0x6b0 [kvm]\n vmx_handle_exit+0x163/0x640 [kvm_intel]\n kvm_arch_vcpu_ioctl_run+0x960/0x2120 [kvm]\n kvm_vcpu_ioctl+0x2c7/0x970 [kvm]\n __x64_sys_ioctl+0x90/0xd0\n do_syscall_64+0x67/0x5f0\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n RIP: 0033:0x7f606d0b53bb\n\nOpportunistically harden the shadow walks against fully invalid roots, but\nWARN, as all callers are expected/required to pre-check for a valid root.\nDon't WARN in the dummy root case as the whole point of using a dummy root\nis to provide a root that's valid enough to enter the guest, i.e. it should\nJust Work for all flows except those that *need* to know about dummy roots.\n\nAlternatively, KVM could allocate a dedicated page and associated shadow\npage structure for the dummy root, which is very tempting as it such an\napproach should be more resilient against unexpected behavior. But that\nwould be a much larger and thus riskier change than simply terminating\nwalks of dummy roots." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/x86/kvm/mmu/mmu.c" ], "versions": [ { "version": "0e3223d8d00ac05849661f1b8b476d3caca251cf", "lessThan": "951fce1510645ba5df38da6fb85ece5726ec347d", "status": "affected", "versionType": "git" }, { "version": "0e3223d8d00ac05849661f1b8b476d3caca251cf", "lessThan": "e1bcabc07efd029ab414894127411129ffdb8b48", "status": "affected", "versionType": "git" }, { "version": "0e3223d8d00ac05849661f1b8b476d3caca251cf", "lessThan": "97c1dcce17ef27853860c781f9912257e6adbf7c", "status": "affected", "versionType": "git" }, { "version": "0e3223d8d00ac05849661f1b8b476d3caca251cf", "lessThan": "681e31f03ec9219099a66a0f6e1bc48e1b5aa914", "status": "affected", "versionType": "git" }, { "version": "0e3223d8d00ac05849661f1b8b476d3caca251cf", "lessThan": "b6249c1d5665098c8bf12f8d3e4712bf04c775bc", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/x86/kvm/mmu/mmu.c" ], "versions": [ { "version": "6.6", "status": "affected" }, { "version": "0", "lessThan": "6.6", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.113", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.56", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.10", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.6.160" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.12.113" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.18.56" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "7.2.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/951fce1510645ba5df38da6fb85ece5726ec347d" }, { "url": "https://git.kernel.org/stable/c/e1bcabc07efd029ab414894127411129ffdb8b48" }, { "url": "https://git.kernel.org/stable/c/97c1dcce17ef27853860c781f9912257e6adbf7c" }, { "url": "https://git.kernel.org/stable/c/681e31f03ec9219099a66a0f6e1bc48e1b5aa914" }, { "url": "https://git.kernel.org/stable/c/b6249c1d5665098c8bf12f8d3e4712bf04c775bc" } ], "title": "KVM: x86/mmu: Bail from shadow walks if the root is invalid or a dummy", "x_generator": { "engine": "bippy-1.2.0" } } } }