CVE-2026-98466 (GCVE-0-2026-98466)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:15 – Updated: 2026-10-24 14:08
VLAI
Title
KVM: arm64: Transfer the hyp stack pages out of the host stage-2
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Transfer the hyp stack pages out of the host stage-2 fix_host_ownership() walks only the linear-map alias of each memblock region, and the per-CPU hyp stack, mapped in the private VA range for its guard page, has none. Walk each stack's VA range with the same walker.
Severity
8.2 (High)
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6794 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1a919b17ef012ca0572bae759c27e5ea02bfb47f , < e5dd2a91a7ae3a276e6d79806127e923936e241b (git)
Affected: 1a919b17ef012ca0572bae759c27e5ea02bfb47f , < 22df195bff84300a3f04813d6148765c77ac565a (git)
Affected: 1a919b17ef012ca0572bae759c27e5ea02bfb47f , < 3a8c562892b96f35bba1e00d5e455a15963bbb92 (git)
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Linux Linux Affected: 5.19
Unaffected: 0 , < 5.19 (semver)
Unaffected: 6.18.55 , ≤ 6.18.* (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/hyp/nvhe/setup.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e5dd2a91a7ae3a276e6d79806127e923936e241b",
              "status": "affected",
              "version": "1a919b17ef012ca0572bae759c27e5ea02bfb47f",
              "versionType": "git"
            },
            {
              "lessThan": "22df195bff84300a3f04813d6148765c77ac565a",
              "status": "affected",
              "version": "1a919b17ef012ca0572bae759c27e5ea02bfb47f",
              "versionType": "git"
            },
            {
              "lessThan": "3a8c562892b96f35bba1e00d5e455a15963bbb92",
              "status": "affected",
              "version": "1a919b17ef012ca0572bae759c27e5ea02bfb47f",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kvm/hyp/nvhe/setup.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.19"
            },
            {
              "lessThan": "5.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.55",
                  "versionStartIncluding": "5.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.9",
                  "versionStartIncluding": "5.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "5.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Transfer the hyp stack pages out of the host stage-2\n\nfix_host_ownership() walks only the linear-map alias of each memblock\nregion, and the per-CPU hyp stack, mapped in the private VA range for\nits guard page, has none.\n\nWalk each stack\u0027s VA range with the same walker."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The local `module_init(kvm_arm_init)` path reaches `init_hyp_mode()` \u2192 `kvm_hyp_init_protection()` \u2192 `do_pkvm_init()` \u2192 `handle___pkvm_init()` \u2192 `__pkvm_init()` \u2192 `__pkvm_init_finalise()` \u2192 patched `fix_host_ownership()`. Exploitation accesses the omitted stack pages through host direct-map aliases; no wire or guest message supplies causal data.\nAC:L - With `kvm-arm.mode=protected`, the omitted pages retain host-owned state, so `handle_host_mem_abort()` \u2192 `host_stage2_idmap()` deterministically installs `PKVM_HOST_MEM_PROT` RWX mappings. The attacker controls the stack access and a following HVC; no race or external condition is required.\nPR:H - `/dev/kvm` ioctls only cause EL2 to use the stack; they do not expose `kvm_arm_hyp_stack_base` or its PFN. Writing the kernel direct-map alias requires control of host EL1 through real host-administrative privilege, unavailable through user namespaces.\nUI:N - After pKVM initialization, the host attacker can access the retained direct-map alias and invoke an HVC or `KVM_RUN` to make EL2 use the corrupted stack. No action by another user is required.\nS:C - The missing `host_stage2_set_owner_locked(..., PKVM_ID_HYP)` operation lets the host EL1 authority access the protected EL2 stack, crossing the stage-2 boundary that isolates the hypervisor and protected VMs.\nC:H - The host can read live EL2 stack contents, including saved registers and pointers. Its simultaneous write access to stack control data can hijack EL2 execution and expose hypervisor or protected-VM memory.\nI:H - The host can overwrite the active stack used by `__host_exit()` and `handle_trap()`, including saved frame and return state. Control-flow corruption at EL2 can modify hypervisor ownership metadata and protected-VM memory.\nA:H - Corrupting the per-CPU stack consumed on every host-to-EL2 trap can produce invalid returns or hypervisor faults, crashing the hypervisor and consequently the host or its protected VMs."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:08:58.562Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e5dd2a91a7ae3a276e6d79806127e923936e241b"
        },
        {
          "url": "https://git.kernel.org/stable/c/22df195bff84300a3f04813d6148765c77ac565a"
        },
        {
          "url": "https://git.kernel.org/stable/c/3a8c562892b96f35bba1e00d5e455a15963bbb92"
        }
      ],
      "title": "KVM: arm64: Transfer the hyp stack pages out of the host stage-2",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98466",
    "datePublished": "2026-10-18T15:15:18.414Z",
    "dateReserved": "2026-09-25T10:25:14.351Z",
    "dateUpdated": "2026-10-24T14:08:58.562Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-98466",
      "date": "2026-11-01",
      "epss": "0.00168",
      "percentile": "0.06132"
    },
    "microsoft_vex": {
      "current_release_date": "2026-11-01T14:54:09.000Z",
      "cve": "CVE-2026-98466",
      "id": "msrc_CVE-2026-98466",
      "initial_release_date": "2026-10-20T01:03:03.000Z",
      "product_status:known_affected": "2",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "KVM: arm64: Transfer the hyp stack pages out of the host stage-2",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98466.json",
      "version": "3"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "arch/arm64/kvm/hyp/nvhe/setup.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
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                    "versionType": "git"
                  },
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                    "versionType": "git"
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                    "versionType": "git"
                  }
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              {
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                "product": "Linux",
                "programFiles": [
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                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
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                    "version": "5.19"
                  },
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                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
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                  {
                    "lessThanOrEqual": "6.18.*",
                    "status": "unaffected",
                    "version": "6.18.55",
                    "versionType": "semver"
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                  {
                    "lessThanOrEqual": "7.2.*",
                    "status": "unaffected",
                    "version": "7.2.9",
                    "versionType": "semver"
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                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "7.3",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Transfer the hyp stack pages out of the host stage-2\n\nfix_host_ownership() walks only the linear-map alias of each memblock\nregion, and the per-CPU hyp stack, mapped in the private VA range for\nits guard page, has none.\n\nWalk each stack\u0027s VA range with the same walker."
          }
        ],
        "id": "CVE-2026-98466",
        "lastModified": "2026-10-24T14:16:43.193",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 8.2,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "HIGH",
                "scope": "CHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.5,
              "impactScore": 6.0,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
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        "published": "2026-10-18T16:16:57.090",
        "references": [
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/22df195bff84300a3f04813d6148765c77ac565a"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/3a8c562892b96f35bba1e00d5e455a15963bbb92"
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/e5dd2a91a7ae3a276e6d79806127e923936e241b"
          }
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
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    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-11-01T22:36:44+00:00",
      "cve": "CVE-2026-98466",
      "id": "CVE-2026-98466",
      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:fixed": "303",
      "product_status:known_affected": "24",
      "product_status:known_not_affected": "168",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: KVM: arm64: Transfer the hyp stack pages out of the host stage-2",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98466.json",
      "version": "3"
    }
  }
}



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