CVE-2026-98639 (GCVE-0-2026-98639)
Vulnerability from cvelistv5
Published
2026-10-18 15:20
Modified
2026-10-19 09:23
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
KVM: riscv: Fix NACL hfence entry update order
The SBI v3.0 specification (section 15.1.2) requires a nested HFENCE
entry to be populated as follows:
1) find an unused entry with Config.Pending == 0
2) update the Page_Number and Page_Count words
3) update the Config word with Config.Pending set
__kvm_riscv_nacl_hfence() writes the Config word first, so the SBI
implementation (or NACL hardware) can observe a pending entry with
pnum/pcount values left over from the previous use of that entry,
resulting in incorrect TLB flush ranges.
Write pnum and pcount first and the Config word last. Since the
consumer is an external agent on coherent shared memory, use
WRITE_ONCE() to stop the compiler from reordering the stores and
smp_wmb() to make the parameter words globally visible before the
Pending bit is set.
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"arch/riscv/kvm/nacl.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "d6de766d8d26d71b714f548192099112def50a9c",
"status": "affected",
"version": "d466c19cead5904d4d5d92adb2b213b411d3b849",
"versionType": "git"
},
{
"lessThan": "6da466502621381fa88a6684290923d25c559266",
"status": "affected",
"version": "d466c19cead5904d4d5d92adb2b213b411d3b849",
"versionType": "git"
},
{
"lessThan": "b3d346838ec65fac7fd83f5dbcedd13cadfffddb",
"status": "affected",
"version": "d466c19cead5904d4d5d92adb2b213b411d3b849",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"arch/riscv/kvm/nacl.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.13"
},
{
"lessThan": "6.13",
"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": "6.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2.9",
"versionStartIncluding": "6.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.3",
"versionStartIncluding": "6.13",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: riscv: Fix NACL hfence entry update order\n\nThe SBI v3.0 specification (section 15.1.2) requires a nested HFENCE\nentry to be populated as follows:\n1) find an unused entry with Config.Pending == 0\n2) update the Page_Number and Page_Count words\n3) update the Config word with Config.Pending set\n\n__kvm_riscv_nacl_hfence() writes the Config word first, so the SBI\nimplementation (or NACL hardware) can observe a pending entry with\npnum/pcount values left over from the previous use of that entry,\nresulting in incorrect TLB flush ranges.\n\nWrite pnum and pcount first and the Config word last. Since the\nconsumer is an external agent on coherent shared memory, use\nWRITE_ONCE() to stop the compiler from reordering the stores and\nsmp_wmb() to make the parameter words globally visible before the\nPending bit is set."
}
],
"providerMetadata": {
"dateUpdated": "2026-10-19T09:23:09.004Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/d6de766d8d26d71b714f548192099112def50a9c"
},
{
"url": "https://git.kernel.org/stable/c/6da466502621381fa88a6684290923d25c559266"
},
{
"url": "https://git.kernel.org/stable/c/b3d346838ec65fac7fd83f5dbcedd13cadfffddb"
}
],
"title": "KVM: riscv: Fix NACL hfence entry update order",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-98639",
"datePublished": "2026-10-18T15:20:10.591Z",
"dateReserved": "2026-09-25T10:25:14.361Z",
"dateUpdated": "2026-10-19T09:23:09.004Z",
"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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