KVM: x86/mmu: Bail from shadow walks if the root is invalid or a dummy

{
  "id": "7a2b9f0b8199a9f879ca5124636e1878e14e05e00aa3ddca5d9f17579af37cce",
  "url": "https://osv.dev/vulnerability/CVE-2026-98717",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "KVM: x86/mmu: Bail from shadow walks if the root is invalid or a dummy",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Bail from shadow walks if the root is invalid or a dummy When walking shadow page tables, immediately terminate the walk if the root is a \"dummy\" root, i.e. a root whose top-level page table is backed by the zero page, but otherwise doesn't exist. If memslot creation races with a stage-2 page fault (EPT violation or #NPF) from L2, then if the stars align, KVM will attempt to walk shadow page tables using the zero page and hit a NULL pointer deref. BUG: kernel NULL pointer dereference, address: 0000000000000021 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP CPU: 30 UID: 1000 PID: 941 Comm: qemu Not tainted 7.2.0-rc2-1b731e5ded48-next-vm #1741 PREEMPTLAZY Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:__kvm_mmu_invalidate_addr+0xea/0x210 [kvm] Call Trace: kvm_mmu_invalidate_addr+0x92/0xe0 [kvm] __kvm_inject_emulated_page_fault+0x67/0x80 [kvm] ept_page_fault+0x160/0x850 [kvm] kvm_mmu_do_page_fault+0x102/0x1f0 [kvm] kvm_mmu_page_fault+0x8e/0x6b0 [kvm] vmx_handle_exit+0x163/0x640 [kvm_intel] kvm_arch_vcpu_ioctl_run+0x960/0x2120 [kvm] kvm_vcpu_ioctl+0x2c7/0x970 [kvm] __x64_sys_ioctl+0x90/0xd0 do_syscall_64+0x67/0x5f0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f606d0b53bb Opportunistically harden the shadow walks against fully invalid roots, but WARN, as all callers are expected/",
    "evidence": "osv:CVE-2026-98717",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.6.160",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.113",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.56",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.10",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98717",
      "aliases": [
        "CVE-2026-98717"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0e3223d8d00ac05849661f1b8b476d3caca251cf"
                },
                {
                  "fixed": "951fce1510645ba5df38da6fb85ece5726ec347d"
                },
                {
                  "fixed": "e1bcabc07efd029ab414894127411129ffdb8b48"
                },
                {
                  "fixed": "97c1dcce17ef27853860c781f9912257e6adbf7c"
                },
                {
                  "fixed": "681e31f03ec9219099a66a0f6e1bc48e1b5aa914"
                },
                {
                  "fixed": "b6249c1d5665098c8bf12f8d3e4712bf04c775bc"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98717.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.6.0"
                },
                {
                  "fixed": "6.6.160"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.113"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.56"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.10"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98717.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.599077506Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/681e31f03ec9219099a66a0f6e1bc48e1b5aa914",
        "https://git.kernel.org/stable/c/951fce1510645ba5df38da6fb85ece5726ec347d",
        "https://git.kernel.org/stable/c/97c1dcce17ef27853860c781f9912257e6adbf7c",
        "https://git.kernel.org/stable/c/b6249c1d5665098c8bf12f8d3e4712bf04c775bc",
        "https://git.kernel.org/stable/c/e1bcabc07efd029ab414894127411129ffdb8b48",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98717.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98717",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98717.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98717",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 518079,
  "published_at": "2026-10-18T15:46:51.862+00:00"
}