CVE-2026-98718 (GCVE-0-2026-98718)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:46 – Updated: 2026-10-19 09:24
VLAI
Title
KVM: SEV: Do cache maintenance on the source VM *before* clearing SEV state
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Do cache maintenance on the source VM *before* clearing SEV state Explicitly flush caches after intra-host migration before clearing "SEV active" on the source VM, as doing cache maintenance afterwards creates a tiny window where memory reclaim could return memory to the host without performing a cache flush, e.g. as pointed out by Sashiko: CPU1 in sev_migrate_from(): src->active = false; CPU2 running concurrent unmap: Since active is false, the automatic cache flush in sev_guest_memory_reclaimed is skipped. The host frees and reallocates the page. CPU1 in sev_migrate_from(): sev_writeback_caches(src_kvm); Executes a hardware cache flush (wbnoinvd), which writes the guest's old dirty ciphertext over the new page owner's data.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6820 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 37dfb676fafd1eef36fe0bb649607afbb0d5521b , < 8b7d4f68fef96cebe0b6dbb6e5607772337f7369 (git)
Affected: d4cc2dff12116a700add601c0262132cc26e1b2c , < de83ff6a4d8f3618473bedb3c4400020c22e8a8a (git)
Affected: 93de2a6a4b91b72607136dd656edf03fb399d27f , < 973ea70393e885e540f714904e51bc6cac80e3d7 (git)
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Linux Linux Affected: 6.18.55 , < 6.18.56 (semver)
Affected: 7.2.9 , < 7.2.10 (semver)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Do cache maintenance on the source VM *before* clearing SEV state\n\nExplicitly flush caches after intra-host migration before clearing \"SEV\nactive\" on the source VM, as doing cache maintenance afterwards creates a\ntiny window where memory reclaim could return memory to the host without\nperforming a cache flush, e.g. as pointed out by Sashiko:\n\n  CPU1 in sev_migrate_from():\n    src-\u003eactive = false;\n\n  CPU2 running concurrent unmap:\n    Since active is false, the automatic cache flush in\n    sev_guest_memory_reclaimed is skipped.\n    The host frees and reallocates the page.\n\n  CPU1 in sev_migrate_from():\n    sev_writeback_caches(src_kvm);\n    Executes a hardware cache flush (wbnoinvd), which writes the guest\u0027s old\n    dirty ciphertext over the new page owner\u0027s data."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:24:29.156Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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          "url": "https://git.kernel.org/stable/c/973ea70393e885e540f714904e51bc6cac80e3d7"
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      ],
      "title": "KVM: SEV: Do cache maintenance on the source VM *before* clearing SEV state",
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    "datePublished": "2026-10-18T15:46:53.611Z",
    "dateReserved": "2026-09-25T10:25:14.366Z",
    "dateUpdated": "2026-10-19T09:24:29.156Z",
    "state": "PUBLISHED"
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Do cache maintenance on the source VM *before* clearing SEV state\n\nExplicitly flush caches after intra-host migration before clearing \"SEV\nactive\" on the source VM, as doing cache maintenance afterwards creates a\ntiny window where memory reclaim could return memory to the host without\nperforming a cache flush, e.g. as pointed out by Sashiko:\n\n  CPU1 in sev_migrate_from():\n    src-\u003eactive = false;\n\n  CPU2 running concurrent unmap:\n    Since active is false, the automatic cache flush in\n    sev_guest_memory_reclaimed is skipped.\n    The host frees and reallocates the page.\n\n  CPU1 in sev_migrate_from():\n    sev_writeback_caches(src_kvm);\n    Executes a hardware cache flush (wbnoinvd), which writes the guest\u0027s old\n    dirty ciphertext over the new page owner\u0027s data."
          }
        ],
        "id": "CVE-2026-98718",
        "lastModified": "2026-10-19T10:19:36.047",
        "metrics": {},
        "published": "2026-10-18T16:17:25.363",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "vulnStatus": "Received"
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      "current_release_date": "2026-10-29T08:18:57+00:00",
      "cve": "CVE-2026-98718",
      "id": "CVE-2026-98718",
      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:known_affected": "236",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: KVM: SEV: Do cache maintenance on the source VM *before* clearing SEV state",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98718.json",
      "version": "3"
    }
  }
}



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