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CVE-2026-89908

Estado: RecibidaAlta (8.8)—

In the Linux kernel, the following vulnerability has been resolved:

LoongArch: KVM: Preserve memslot arch flags on KVM_MR_FLAGS_ONLY

kvm_arch_prepare_memory_region() computes new->arch.flags, i.e. whether a memslot is KVM_MEM_HUGEPAGE_CAPABLE or KVM_MEM_HUGEPAGE_INCAPABLE, only for KVM_MR_CREATE and KVM_MR_MOVE, and returns early for every other change. But the generic code allocates a zeroed memslot for every change and never copies old->arch, so after a KVM_MR_FLAGS_ONLY update, e.g. toggling KVM_MEM_LOG_DIRTY_PAGES for live migration, the active memslot has arch.flags == 0.

With both flags clear, fault_supports_huge_mapping() falls through to the alignment check on the HVA range alone, which no longer verifies that the GPA and HVA have the same offset within a PMD.

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A memslot that was marked KVM_MEM_HUGEPAGE_INCAPABLE because of a GPA/HVA offset mismatch can then be mapped with PMD entries on read faults, and since kvm_map_page() aligns the gfn and the pfn independently, the guest ends up accessing the wrong host pages, exactly the "d -> f, e -> g" case described in the comment above the check.

Carry the arch flags over from the old memslot for KVM_MR_FLAGS_ONLY, as the GPA, HVA and size are guaranteed to be unchanged for that case.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Escalada de privilegios local en kernel Linux (AV:L, PR:L) mediante corrupción de memoria en KVM que permite acceso a páginas de host incorrectas (C:H, I:H)

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Threat Intelligence ProgramRestrict File and Directory PermissionsRemote Data StorageExecution PreventionEncrypt Sensitive InformationApplication Isolation and Sandboxing

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux KernelAI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-89908",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 8.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 6,
        "exploitabilityScore": 2
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c",
              "lessThan": "7c6df65b53846cd7a9a1c81c6ddb42fdc08603e8",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c",
              "lessThan": "4e4dbc341b1581dc512b85d98b768373b0398366",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c",
              "lessThan": "bc7a6849b4395f45a602db91b0fb2fb2e9ed4bba",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "7ab6fb505b2a7447c4a7237a12c59e3ad0c7298c",
              "lessThan": "27a9bfee3bbcb3cabb77797354f07e0e44e49831",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "arch/loongarch/kvm/mmu.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.8",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.110",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "arch/loongarch/kvm/mmu.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-16T11:16:59.807",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/27a9bfee3bbcb3cabb77797354f07e0e44e49831",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/4e4dbc341b1581dc512b85d98b768373b0398366",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/7c6df65b53846cd7a9a1c81c6ddb42fdc08603e8",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/bc7a6849b4395f45a602db91b0fb2fb2e9ed4bba",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nLoongArch: KVM: Preserve memslot arch flags on KVM_MR_FLAGS_ONLY\n\nkvm_arch_prepare_memory_region() computes new->arch.flags, i.e. whether\na memslot is KVM_MEM_HUGEPAGE_CAPABLE or KVM_MEM_HUGEPAGE_INCAPABLE,\nonly for KVM_MR_CREATE and KVM_MR_MOVE, and returns early for every\nother change. But the generic code allocates a zeroed memslot for every\nchange and never copies old->arch, so after a KVM_MR_FLAGS_ONLY update,\ne.g. toggling KVM_MEM_LOG_DIRTY_PAGES for live migration, the active\nmemslot has arch.flags == 0.\n\nWith both flags clear, fault_supports_huge_mapping() falls through to\nthe alignment check on the HVA range alone, which no longer verifies\nthat the GPA and HVA have the same offset within a PMD. A memslot that\nwas marked KVM_MEM_HUGEPAGE_INCAPABLE because of a GPA/HVA offset\nmismatch can then be mapped with PMD entries on read faults, and since\nkvm_map_page() aligns the gfn and the pfn independently, the guest ends\nup accessing the wrong host pages, exactly the \"d -> f, e -> g\" case\ndescribed in the comment above the check.\n\nCarry the arch flags over from the old memslot for KVM_MR_FLAGS_ONLY,\nas the GPA, HVA and size are guaranteed to be unchanged for that case."
    }
  ],
  "lastModified": "2026-09-16T15:18:17.050",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}