CVE-2026-64284 (GCVE-0-2026-64284)
Vulnerability from cvelistv5
Published
2026-07-25 08:49
Modified
2026-08-17 04:52
Severity ?
VLAI Severity ?
EPSS score ?
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.
References
| URL | Tags | |
|---|---|---|
Impacted products
{
"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"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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