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CVE-2026-89957

Estado: RecibidaAlta (8.8)—

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

s390/vfio-ap: Fix hot-unplug skipped when last AP adapter or domain removed

The vfio_ap_mdev_hot_unplug_cfg() function uses the return value of bitmap_andnot() to determine whether the guest APCB needs to be updated. However, bitmap_andnot() returns false when the resulting destination bitmap is empty.

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This means that if the only adapter, domain or control domain assigned to an mdev is removed from the host's AP configuration, the bit is correctly cleared from the shadow APCB, but bitmap_andnot() returns false because the result is an empty bitmap. Consequently, do_hotplug remains 0 and vfio_ap_mdev_update_guest_apcb() is never called, leaving the KVM guest with stale hardware access to the unplugged AP devices.

Fix this by replacing the bitmap_andnot() return value check with bitmap_intersects() to determine whether the shadow APCB actually overlaps with the removal mask. If there is an intersection, call bitmap_andnot() solely for its side effect of clearing the bits, then unconditionally set do_hotplug to trigger the guest APCB update.

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.

Inferido por reglas deterministas a partir del vector CVSS y la CWE. Solo orientativo.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Threat Intelligence ProgramExecution PreventionApplication Isolation and SandboxingExploit ProtectionUpdate Software

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-2026-89957",
  "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": "eeb386aeb5b7c8d2dae6a3ba49255d8a97803182",
              "lessThan": "f58e824de8577fe411f6199d659731a0f86a7275",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "eeb386aeb5b7c8d2dae6a3ba49255d8a97803182",
              "lessThan": "3a9b049bbdc40165d7f3e20b818eec95e5694d96",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "eeb386aeb5b7c8d2dae6a3ba49255d8a97803182",
              "lessThan": "753aa3bb1273bc0d36adb013d5915cc8ff6b72a9",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "eeb386aeb5b7c8d2dae6a3ba49255d8a97803182",
              "lessThan": "c45753c32d452d10d8efaeb52587e9e6e8126e33",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "eeb386aeb5b7c8d2dae6a3ba49255d8a97803182",
              "lessThan": "04b35dd88c108b2d2ceaaa396aba1cb4049d5831",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "eeb386aeb5b7c8d2dae6a3ba49255d8a97803182",
              "lessThan": "917f509bfb88048094dbb85c4e9dbc4d6fe4a886",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "drivers/s390/crypto/vfio_ap_ops.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.0"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "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": [
            "drivers/s390/crypto/vfio_ap_ops.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-16T11:17:06.043",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/04b35dd88c108b2d2ceaaa396aba1cb4049d5831",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/3a9b049bbdc40165d7f3e20b818eec95e5694d96",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/753aa3bb1273bc0d36adb013d5915cc8ff6b72a9",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/917f509bfb88048094dbb85c4e9dbc4d6fe4a886",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/c45753c32d452d10d8efaeb52587e9e6e8126e33",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f58e824de8577fe411f6199d659731a0f86a7275",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio-ap: Fix hot-unplug skipped when last AP adapter or domain removed\n\nThe vfio_ap_mdev_hot_unplug_cfg() function uses the return value of\nbitmap_andnot() to determine whether the guest APCB needs to be updated.\nHowever, bitmap_andnot() returns false when the resulting destination\nbitmap is empty. This means that if the only adapter, domain or control\ndomain assigned to an mdev is removed from the host's AP configuration,\nthe bit is correctly cleared from the shadow APCB, but bitmap_andnot()\nreturns false because the result is an empty bitmap. Consequently,\ndo_hotplug remains 0 and vfio_ap_mdev_update_guest_apcb() is never called,\nleaving the KVM guest with stale hardware access to the unplugged AP\ndevices.\n\nFix this by replacing the bitmap_andnot() return value check with\nbitmap_intersects() to determine whether the shadow APCB actually\noverlaps with the removal mask. If there is an intersection, call\nbitmap_andnot() solely for its side effect of clearing the bits, then\nunconditionally set do_hotplug to trigger the guest APCB update."
    }
  ],
  "lastModified": "2026-09-16T15:18:20.280",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}