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CVE-2026-89920

Estado: RecibidaAlta (7.8)—

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

KVM: s390: Fix memory corruption by not reinjecting CK machine checks

Channel-subsystem damage machine checks are for the host channel subsystem. The guest channel subsystem is emulated in the userspace VMM. There is no point in forwarding such machine checks into the guest.

This also simplifies the machine check reinjection and avoids kfree of a stack variable as reported by sashiko. There might be still machine checks that have the ck bit set with another bit (like instruction damage), mask out the CK bit in s390_backup_mcck_info(), like the CP and ED bits already are.

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 kernel (AV:L, PR:L) que causa corrupción de memoria por reininyección incorrecta de machine checks. Permite lectura (C:H) y modificación de datos (I:H) 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 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-2026-89920",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "HIGH",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 6,
        "exploitabilityScore": 1.1
      }
    ]
  },
  "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": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
              "lessThan": "6ee52d3af2a1bf70349cf3f860933c8d221e229a",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
              "lessThan": "7077ec953996acc04b49d1dfc43df1c1a2a74395",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
              "lessThan": "546dde823a36d7283dcf46127c2f3d093443860f",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "arch/s390/include/asm/nmi.h",
            "arch/s390/kernel/nmi.c",
            "arch/s390/kvm/interrupt.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.13"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "4.13",
              "versionType": "semver"
            },
            {
              "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/s390/include/asm/nmi.h",
            "arch/s390/kernel/nmi.c",
            "arch/s390/kvm/interrupt.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-16T11:17:01.073",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/546dde823a36d7283dcf46127c2f3d093443860f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6ee52d3af2a1bf70349cf3f860933c8d221e229a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/7077ec953996acc04b49d1dfc43df1c1a2a74395",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: s390: Fix memory corruption by not reinjecting CK machine checks\n\nChannel-subsystem damage machine checks are for the host channel\nsubsystem. The guest channel subsystem is emulated in the userspace VMM.\nThere is no point in forwarding such machine checks into the guest.\n\nThis also simplifies the machine check reinjection and avoids kfree of a\nstack variable as reported by sashiko.  There might be still machine\nchecks that have the ck bit set with another bit (like instruction\ndamage), mask out the CK bit in s390_backup_mcck_info(), like the CP and\nED bits already are."
    }
  ],
  "lastModified": "2026-09-16T15:18:18.237",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}