Vulnerability-Lookup

GHSA-8J5C-4J8R-8M5M

Vulnerability from github – Published: 2026-10-18 18:32 – Updated: 2026-10-18 18:32

Details

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.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98718"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T16:17:25Z",
    "severity": null
  },
  "details": "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": "GHSA-8j5c-4j8r-8m5m",
  "modified": "2026-10-18T18:32:00Z",
  "published": "2026-10-18T18:32:00Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98718"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8b7d4f68fef96cebe0b6dbb6e5607772337f7369"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/973ea70393e885e540f714904e51bc6cac80e3d7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/de83ff6a4d8f3618473bedb3c4400020c22e8a8a"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

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

Vulnerability from cvelistv5 – Published: 2026-10-18 15:46 – Updated: 2026-10-19 09:24

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

3 references

URL	Tags
https://git.kernel.org/stable/c/8b7d4f68fef96cebe…
https://git.kernel.org/stable/c/de83ff6a4d8f36184…
https://git.kernel.org/stable/c/973ea70393e885e54…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 37dfb676fafd1eef36fe0bb649607afbb0d5521b , < 8b7d4f68fef96cebe0b6dbb6e5607772337f7369 (git) Affected: d4cc2dff12116a700add601c0262132cc26e1b2c , < de83ff6a4d8f3618473bedb3c4400020c22e8a8a (git) Affected: 93de2a6a4b91b72607136dd656edf03fb399d27f , < 973ea70393e885e540f714904e51bc6cac80e3d7 (git)
Linux	Linux	Affected: 6.18.55 , < 6.18.56 (semver) Affected: 7.2.9 , < 7.2.10 (semver)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/kvm/svm/sev.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "8b7d4f68fef96cebe0b6dbb6e5607772337f7369",
              "status": "affected",
              "version": "37dfb676fafd1eef36fe0bb649607afbb0d5521b",
              "versionType": "git"
            },
            {
              "lessThan": "de83ff6a4d8f3618473bedb3c4400020c22e8a8a",
              "status": "affected",
              "version": "d4cc2dff12116a700add601c0262132cc26e1b2c",
              "versionType": "git"
            },
            {
              "lessThan": "973ea70393e885e540f714904e51bc6cac80e3d7",
              "status": "affected",
              "version": "93de2a6a4b91b72607136dd656edf03fb399d27f",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/kvm/svm/sev.c"
          ],
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          "vendor": "Linux",
          "versions": [
            {
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              "status": "affected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThan": "7.2.10",
              "status": "affected",
              "version": "7.2.9",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.56",
                  "versionStartIncluding": "6.18.55",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.10",
                  "versionStartIncluding": "7.2.9",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:24:29.156Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/8b7d4f68fef96cebe0b6dbb6e5607772337f7369"
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        },
        {
          "url": "https://git.kernel.org/stable/c/973ea70393e885e540f714904e51bc6cac80e3d7"
        }
      ],
      "title": "KVM: SEV: Do cache maintenance on the source VM *before* clearing SEV state",
      "x_generator": {
        "engine": "bippy-1.2.0"
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98718",
    "datePublished": "2026-10-18T15:46:53.611Z",
    "dateReserved": "2026-09-25T10:25:14.366Z",
    "dateUpdated": "2026-10-19T09:24:29.156Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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