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GHSA-HQMW-J6G2-75M9

Vulnerability from github – Published: 2026-10-18 18:31 – Updated: 2026-10-24 15:32

Details

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

KVM: SEV: Do cache maintenance on the source VM during intra-host migration

Manually perform cache maintenance on the source VM during intra-host migration to ensure no stale data is left in CPU caches after the VM is destroyed. Because the source VM is "converted" to a non-SEV VM, KVM's memory reclaim flows won't trigger cache maintenance, e.g. when all guest memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option as KVM doesn't require identical guest memory configurations, i.e. the source VM may have access to memory that the destination VM does not. Enforcing equivalent memory configurations is infeasible, as it would require a deep comparison of memslots, e.g. to verify that not only are the memslot identical, but what the memslots point at is also identical.

Severity

7.1 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98471"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T16:16:57Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Do cache maintenance on the source VM during intra-host migration\n\nManually perform cache maintenance on the source VM during intra-host\nmigration to ensure no stale data is left in CPU caches after the VM is\ndestroyed.  Because the source VM is \"converted\" to a non-SEV VM, KVM\u0027s\nmemory reclaim flows won\u0027t trigger cache maintenance, e.g. when all guest\nmemory is reclaimed in response to detaching from the mmu_notifier.\n\nNote, relying on the destination VM to do cache maintenance isn\u0027t an option\nas KVM doesn\u0027t require identical guest memory configurations, i.e. the\nsource VM may have access to memory that the destination VM does not.\nEnforcing equivalent memory configurations is infeasible, as it would\nrequire a *deep* comparison of memslots, e.g. to verify that not only are\nthe memslot identical, but what the memslots point at is also identical.",
  "id": "GHSA-hqmw-j6g2-75m9",
  "modified": "2026-10-24T15:32:46Z",
  "published": "2026-10-18T18:31:50Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98471"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/37dfb676fafd1eef36fe0bb649607afbb0d5521b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/93de2a6a4b91b72607136dd656edf03fb399d27f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d4cc2dff12116a700add601c0262132cc26e1b2c"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-98471 (GCVE-0-2026-98471)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:15 – Updated: 2026-10-24 14:09

Title

KVM: SEV: Do cache maintenance on the source VM during intra-host migration

Summary

In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Do cache maintenance on the source VM during intra-host migration Manually perform cache maintenance on the source VM during intra-host migration to ensure no stale data is left in CPU caches after the VM is destroyed. Because the source VM is "converted" to a non-SEV VM, KVM's memory reclaim flows won't trigger cache maintenance, e.g. when all guest memory is reclaimed in response to detaching from the mmu_notifier. Note, relying on the destination VM to do cache maintenance isn't an option as KVM doesn't require identical guest memory configurations, i.e. the source VM may have access to memory that the destination VM does not. Enforcing equivalent memory configurations is infeasible, as it would require a *deep* comparison of memslots, e.g. to verify that not only are the memslot identical, but what the memslots point at is also identical.

Severity

7.1 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6639 records in the last 180 days details

References

3 references

URL	Tags
https://git.kernel.org/stable/c/37dfb676fafd1eef3…
https://git.kernel.org/stable/c/d4cc2dff12116a700…
https://git.kernel.org/stable/c/93de2a6a4b91b7260…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: b56639318bb2be66aceba92836279714488709b4 , < 37dfb676fafd1eef36fe0bb649607afbb0d5521b (git) Affected: b56639318bb2be66aceba92836279714488709b4 , < d4cc2dff12116a700add601c0262132cc26e1b2c (git) Affected: b56639318bb2be66aceba92836279714488709b4 , < 93de2a6a4b91b72607136dd656edf03fb399d27f (git)
Linux	Linux	Affected: 5.16 Unaffected: 0 , < 5.16 (semver) Unaffected: 6.18.55 , ≤ 6.18.* (semver) Unaffected: 7.2.9 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

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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": "37dfb676fafd1eef36fe0bb649607afbb0d5521b",
              "status": "affected",
              "version": "b56639318bb2be66aceba92836279714488709b4",
              "versionType": "git"
            },
            {
              "lessThan": "d4cc2dff12116a700add601c0262132cc26e1b2c",
              "status": "affected",
              "version": "b56639318bb2be66aceba92836279714488709b4",
              "versionType": "git"
            },
            {
              "lessThan": "93de2a6a4b91b72607136dd656edf03fb399d27f",
              "status": "affected",
              "version": "b56639318bb2be66aceba92836279714488709b4",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "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": [
            {
              "status": "affected",
              "version": "5.16"
            },
            {
              "lessThan": "5.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.55",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.9",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "5.16",
                  "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 during intra-host migration\n\nManually perform cache maintenance on the source VM during intra-host\nmigration to ensure no stale data is left in CPU caches after the VM is\ndestroyed.  Because the source VM is \"converted\" to a non-SEV VM, KVM\u0027s\nmemory reclaim flows won\u0027t trigger cache maintenance, e.g. when all guest\nmemory is reclaimed in response to detaching from the mmu_notifier.\n\nNote, relying on the destination VM to do cache maintenance isn\u0027t an option\nas KVM doesn\u0027t require identical guest memory configurations, i.e. the\nsource VM may have access to memory that the destination VM does not.\nEnforcing equivalent memory configurations is infeasible, as it would\nrequire a *deep* comparison of memslots, e.g. to verify that not only are\nthe memslot identical, but what the memslots point at is also identical."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - A host process reaches patched sev_migrate_from() only through ioctl(KVM_ENABLE_CAP) -\u003e kvm_vm_ioctl_enable_cap_generic() -\u003e kvm_vm_ioctl_enable_cap() with KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM and source/destination VM fds; no network input reaches this path.\nAC:L - The caller can run its SEV source to create dirty guest cache lines, give the destination different memslots, issue MOVE, and unmap source-only RAM; no race or victim-controlled state is required.\nPR:L - The path requires usable /dev/kvm and /dev/sev fds plus both VM fds, but neither kvm_vm_ioctl_enable_cap() nor sev_vm_move_enc_context_from() checks a capability; this is low-privilege KVM/SEV device access, not init-namespace root.\nUI:N - The same VMM process can create and run the source, construct the destination, invoke KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM, and release source-only memory without another user\u0027s action.\nS:U - The attacker invokes a host ioctl and the resulting stale writeback corrupts host-owned memory; this is a local userspace-to-kernel violation, not a guest-to-host escape or IOMMU boundary bypass.\nC:N - sev_writeback_caches() protects against dirty-line writeback; omitting it creates a delayed ciphertext overwrite of reused memory, but the examined path provides no read primitive or way to recover another encryption domain\u0027s plaintext.\nI:H - After sev_migrate_from() clears src-\u003eactive, sev_guest_memory_reclaimed() skips flushing; later eviction of a dirty source-only line can overwrite a full cache line in a page already reassigned to another user, including kernel objects or page tables.\nA:H - The delayed overwrite can corrupt live slab or page-table state and oops or panic the host; the same SEV reclaim-flush mechanism was introduced because repeated malicious allocation and release of unflushed encrypted pages can crash the host."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:09:00.765Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/37dfb676fafd1eef36fe0bb649607afbb0d5521b"
        },
        {
          "url": "https://git.kernel.org/stable/c/d4cc2dff12116a700add601c0262132cc26e1b2c"
        },
        {
          "url": "https://git.kernel.org/stable/c/93de2a6a4b91b72607136dd656edf03fb399d27f"
        }
      ],
      "title": "KVM: SEV: Do cache maintenance on the source VM during intra-host migration",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98471",
    "datePublished": "2026-10-18T15:15:23.690Z",
    "dateReserved": "2026-09-25T10:25:14.351Z",
    "dateUpdated": "2026-10-24T14:09:00.765Z",
    "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.

Vulnerability timeline

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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