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CVE-2026-89961

Estado: RecibidaAlta (7.8)—

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

powerpc/mm: fix wrong addr_pfn tracking in compound vmemmap population

vmemmap_populate_compound_pages() uses addr_pfn to determine the PFN offset within a compound page and to decide whether the current vmemmap slot should be populated as a head page mapping or should reuse a tail page mapping.

However, addr_pfn is advanced manually in parallel with addr. The loop itself progresses in vmemmap address space, so each PAGE_SIZE step in addr covers PAGE_SIZE / sizeof(struct page) struct page slots.

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Since addr_pfn is compared against nr_pages in data-PFN units, it should advance by the same number of PFNs. The existing manual increments do not match that and therefore do not reliably track the PFN corresponding to the current addr.

As a result, pfn_offset can be computed from the wrong PFN and the code can make the head/tail decision for the wrong compound-page position.

Fix this by deriving addr_pfn directly from the current vmemmap address instead of carrying it as loop state.

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.

Vulnerabilidad local de corrupción de memoria en kernel (AV:L, PR:L) que permite escalada. El error en vmemmap afecta integridad de datos y puede causar DoS; explotable con privilegios locales.

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 StorageFilter Network TrafficExecution PreventionEncrypt Sensitive Information

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-2026-89961",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      }
    ]
  },
  "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": "f2b79c0d79683d552369bb9a7282c1f0226fc566",
              "lessThan": "b96be860673f9fbbf12cdadb0b25fc4d6d4d207f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "f2b79c0d79683d552369bb9a7282c1f0226fc566",
              "lessThan": "e163c7184acf36ac20a248498f4a16016057ca01",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "f2b79c0d79683d552369bb9a7282c1f0226fc566",
              "lessThan": "9c914b7a0bd18834505c65f22225ce22c152b2d9",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "f2b79c0d79683d552369bb9a7282c1f0226fc566",
              "lessThan": "7968852a7ca3ce81477ec5b4494a28d612f35a97",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "f2b79c0d79683d552369bb9a7282c1f0226fc566",
              "lessThan": "89a4ae32764172468dea303eb6ae90fe6c859712",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "arch/powerpc/mm/book3s64/radix_pgtable.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.6"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.6",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "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-rc1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "arch/powerpc/mm/book3s64/radix_pgtable.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-16T11:17:06.570",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/7968852a7ca3ce81477ec5b4494a28d612f35a97",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/89a4ae32764172468dea303eb6ae90fe6c859712",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9c914b7a0bd18834505c65f22225ce22c152b2d9",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b96be860673f9fbbf12cdadb0b25fc4d6d4d207f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/e163c7184acf36ac20a248498f4a16016057ca01",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/mm: fix wrong addr_pfn tracking in compound vmemmap population\n\nvmemmap_populate_compound_pages() uses addr_pfn to determine the PFN\noffset within a compound page and to decide whether the current vmemmap\nslot should be populated as a head page mapping or should reuse a tail\npage mapping.\n\nHowever, addr_pfn is advanced manually in parallel with addr.  The loop\nitself progresses in vmemmap address space, so each PAGE_SIZE step in addr\ncovers PAGE_SIZE / sizeof(struct page) struct page slots.  Since addr_pfn\nis compared against nr_pages in data-PFN units, it should advance by the\nsame number of PFNs.  The existing manual increments do not match that and\ntherefore do not reliably track the PFN corresponding to the current addr.\n\nAs a result, pfn_offset can be computed from the wrong PFN and the code\ncan make the head/tail decision for the wrong compound-page position.\n\nFix this by deriving addr_pfn directly from the current vmemmap address\ninstead of carrying it as loop state."
    }
  ],
  "lastModified": "2026-09-16T15:18:20.703",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}