Vulnerability-Lookup

GHSA-GV38-JCPJ-J76H

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-27 06:30

Details

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

KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits

Move the handling of fastpath userspace exits into vendor code to ensure KVM runs vendor specific operations that need to run before userspace gains control of the vCPU. E.g. for VMX (and soon to be for SVM as well), KVM needs to flush the PML buffer prior to exiting to userspace, otherwise any memory written by the final KVM_RUN might never be flagged as dirty.

Note, waiting to snapshot CR0 and CR3 until svm_handle_exit() is flawed in general, as that risks consuming stale state in a fastpath handler. That will be addressed in a future change.

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-2026-64284"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:09Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86: Ensure vendor\u0027s exit handler runs before fastpath userspace exits\n\nMove the handling of fastpath userspace exits into vendor code to ensure\nKVM runs vendor specific operations that need to run before userspace gains\ncontrol of the vCPU.  E.g. for VMX (and soon to be for SVM as well), KVM\nneeds to flush the PML buffer prior to exiting to userspace, otherwise any\nmemory written by the final KVM_RUN might never be flagged as dirty.\n\nNote, waiting to snapshot CR0 and CR3 until svm_handle_exit() is flawed in\ngeneral, as that risks consuming stale state in a fastpath handler.  That\nwill be addressed in a future change.",
  "id": "GHSA-gv38-jcpj-j76h",
  "modified": "2026-07-27T06:30:31Z",
  "published": "2026-07-25T12:31:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64284"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0ffedf43910e44b76c2c1db4e9fbf12b268190c1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4ad73ef0e7966ecfe67de0060537b4cb14d9acd4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b3436d9b9b1affe1c3191ac9831308923f5f03c3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f2ca2b5326211bd38490f0497eb583721ce0bbc0"
    }
  ],
  "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-2026-64284 (GCVE-0-2026-64284)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:49 – Updated: 2026-08-17 04:52

Title

KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits

Summary

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits Move the handling of fastpath userspace exits into vendor code to ensure KVM runs vendor specific operations that need to run before userspace gains control of the vCPU. E.g. for VMX (and soon to be for SVM as well), KVM needs to flush the PML buffer prior to exiting to userspace, otherwise any memory written by the final KVM_RUN might never be flagged as dirty. Note, waiting to snapshot CR0 and CR3 until svm_handle_exit() is flawed in general, as that risks consuming stale state in a fastpath handler. That will be addressed in a future change.

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 mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/b3436d9b9b1affe1c…
https://git.kernel.org/stable/c/4ad73ef0e7966ecfe…
https://git.kernel.org/stable/c/f2ca2b5326211bd38…
https://git.kernel.org/stable/c/0ffedf43910e44b76…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: f7f39c50edb9d336274371953275e0d3503b9b75 , < b3436d9b9b1affe1c3191ac9831308923f5f03c3 (git) Affected: f7f39c50edb9d336274371953275e0d3503b9b75 , < 4ad73ef0e7966ecfe67de0060537b4cb14d9acd4 (git) Affected: f7f39c50edb9d336274371953275e0d3503b9b75 , < f2ca2b5326211bd38490f0497eb583721ce0bbc0 (git) Affected: f7f39c50edb9d336274371953275e0d3503b9b75 , < 0ffedf43910e44b76c2c1db4e9fbf12b268190c1 (git)
Linux	Linux	Affected: 6.12 Unaffected: 0 , < 6.12 (semver) Unaffected: 6.12.96 , ≤ 6.12.* (semver) Unaffected: 6.18.39 , ≤ 6.18.* (semver) Unaffected: 7.1.4 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/kvm/svm/svm.c",
            "arch/x86/kvm/vmx/vmx.c",
            "arch/x86/kvm/x86.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "b3436d9b9b1affe1c3191ac9831308923f5f03c3",
              "status": "affected",
              "version": "f7f39c50edb9d336274371953275e0d3503b9b75",
              "versionType": "git"
            },
            {
              "lessThan": "4ad73ef0e7966ecfe67de0060537b4cb14d9acd4",
              "status": "affected",
              "version": "f7f39c50edb9d336274371953275e0d3503b9b75",
              "versionType": "git"
            },
            {
              "lessThan": "f2ca2b5326211bd38490f0497eb583721ce0bbc0",
              "status": "affected",
              "version": "f7f39c50edb9d336274371953275e0d3503b9b75",
              "versionType": "git"
            },
            {
              "lessThan": "0ffedf43910e44b76c2c1db4e9fbf12b268190c1",
              "status": "affected",
              "version": "f7f39c50edb9d336274371953275e0d3503b9b75",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/kvm/svm/svm.c",
            "arch/x86/kvm/vmx/vmx.c",
            "arch/x86/kvm/x86.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "lessThan": "6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.96",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.39",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.4",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86: Ensure vendor\u0027s exit handler runs before fastpath userspace exits\n\nMove the handling of fastpath userspace exits into vendor code to ensure\nKVM runs vendor specific operations that need to run before userspace gains\ncontrol of the vCPU.  E.g. for VMX (and soon to be for SVM as well), KVM\nneeds to flush the PML buffer prior to exiting to userspace, otherwise any\nmemory written by the final KVM_RUN might never be flagged as dirty.\n\nNote, waiting to snapshot CR0 and CR3 until svm_handle_exit() is flawed in\ngeneral, as that risks consuming stale state in a fastpath handler.  That\nwill be addressed in a future change."
        }
      ],
      "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 - The vulnerable path is reached through guest execution under the local KVM_RUN ioctl, not through network input.\nAC:L - With PML dirty logging active, the attacker can control guest writes and repeatedly force fastpath userspace exits such as HLT; no uncontrollable race must be won.\nPR:L - KVM_RUN and guest-debug operations require access to the VM\u0027s vCPU file descriptor but perform no capability or init-namespace root check.\nUI:N - No human interaction is required because migration and snapshot processing can be automated while guest code supplies the triggering exits.\nS:U - The flaw corrupts the affected VM\u0027s migration or saved state but does not provide host privilege escalation, host-memory access, or a guest-to-host escape.\nC:N - The incomplete dirty log does not expose memory contents or give the attacker a read primitive.\nI:H - Attacker-selected guest writes can be omitted from the final dirty bitmap, causing arbitrary guest pages to be restored with stale contents and substantially corrupting migrated state.\nA:H - Stale CR state or corrupted guest memory can make a migrated or restored VM crash, hang, or fail to resume."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:52:39.824Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/b3436d9b9b1affe1c3191ac9831308923f5f03c3"
        },
        {
          "url": "https://git.kernel.org/stable/c/4ad73ef0e7966ecfe67de0060537b4cb14d9acd4"
        },
        {
          "url": "https://git.kernel.org/stable/c/f2ca2b5326211bd38490f0497eb583721ce0bbc0"
        },
        {
          "url": "https://git.kernel.org/stable/c/0ffedf43910e44b76c2c1db4e9fbf12b268190c1"
        }
      ],
      "title": "KVM: x86: Ensure vendor\u0027s exit handler runs before fastpath userspace exits",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64284",
    "datePublished": "2026-07-25T08:49:26.270Z",
    "dateReserved": "2026-07-19T15:36:31.777Z",
    "dateUpdated": "2026-08-17T04:52:39.824Z",
    "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.

Detection rules are retrieved from Rulezet.

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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

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