CVE-2026-64247
Estado: AnalizadaAlta (8.4)—
In the Linux kernel, the following vulnerability has been resolved:
KVM: x86: hyper-v: Bound the bank index when querying sparse banks
When checking if a VP ID is included in a sparse bank set, explicitly check that the ID can actually be contained in a sparse bank (the TLFS allows for a maximum of 64 banks of 64 vCPUs each). When handling a paravirtual TLB flush for L2, the VP ID is copied verbatim from the enlightened VMCS, without any bounds check, i.e. isn't guaranteed to be under the limit of 4096.
Failure to check the bounds of the VP ID leads to an out-of-bounds read when testing the sparse bank, and super strictly speaking could lead to KVM performing an unnecessary TLB flush for an L2 vCPU.
Leer descripción completaMostrar menos
Opportunistically add a compile time assertion to ensure the maximum number of sparse banks exactly matches the number of possible bits in the passed in mask.
[sean: add KASAN splat, drop comment, add assert, massage changelog]
Detalles técnicos trazas, registros y código del informe original
==================================================================
BUG: KASAN: use-after-free in hv_is_vp_in_sparse_set+0x85/0x100 [kvm]
Read of size 8 at addr ffff88811ba5f598 by task hyperv_evmcs/2802
CPU: 12 UID: 1000 PID: 2802 Comm: hyperv_evmcs Not tainted 7.1.0-rc2 #7 PREEMPT
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Call Trace:
<TASK>
dump_stack_lvl+0x51/0x60
print_report+0xcb/0x5d0
kasan_report+0xb4/0xe0
kasan_check_range+0x35/0x1b0
hv_is_vp_in_sparse_set+0x85/0x100 [kvm]
kvm_hv_flush_tlb+0xe9e/0x16c0 [kvm]
kvm_hv_hypercall+0xe6b/0x1e60 [kvm]
vmx_handle_exit+0x485/0x1b60 [kvm_intel]
kvm_arch_vcpu_ioctl_run+0x22e3/0x5070 [kvm]
kvm_vcpu_ioctl+0x5d0/0x10c0 [kvm]
__x64_sys_ioctl+0x129/0x1a0
do_syscall_64+0xb9/0xcf0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7f0e62d1a9bf
</TASK>
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffffffffffffffff pfn:0x11ba5f
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 0000000000000000 00000000ffffffff 0000000000000000
raw: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff88811ba5f480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88811ba5f500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88811ba5f580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88811ba5f600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88811ba5f680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
Disabling lock debugging due to kernel taintCVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:H
- Puntuación base: 8.4
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.11%
- Percentil entre todas las CVEs puntuadas: 1
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation85 % - Impacto principal
T1005Data from Local Systemcollection75 % - Impacto secundario
T1499.004Application or System Exploitationimpact65 %
AV:L/PR:L sin UI indica escalada local. Out-of-bounds read en kernel KVM permite lectura de memoria; DoS potencial por TLB flush innecesario en hipervisor.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
CWE
- CWE-125
Referencias
- https://git.kernel.org/stable/c/4721f8160f17554b003e8928bb61e6c9b2fe92a3
- https://git.kernel.org/stable/c/83c2f52c6a78b1590034e955cff3fe0b052fe4ae
- https://git.kernel.org/stable/c/d18756b12aab30d07794446445c93112e5c69a2e
- https://git.kernel.org/stable/c/e36095d8d922bb26ce860231aacf0cd14edea07c
- https://git.kernel.org/stable/c/f636cf6a1e7b7f40d48d8d08bd5f152aa61dd130
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-64247",
"cveTags": [],
"metrics": {
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"type": "Secondary",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"version": "3.1",
"baseScore": 8.4,
"attackVector": "LOCAL",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "HIGH"
},
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"exploitabilityScore": 2
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"version": "6.18.38",
"versionType": "semver",
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{
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"versionType": "semver",
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"published": "2026-07-24T16:16:54.147",
"references": [
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"weaknesses": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
"value": "CWE-125"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86: hyper-v: Bound the bank index when querying sparse banks\n\nWhen checking if a VP ID is included in a sparse bank set, explicitly check\nthat the ID can actually be contained in a sparse bank (the TLFS allows for\na maximum of 64 banks of 64 vCPUs each). When handling a paravirtual TLB\nflush for L2, the VP ID is copied verbatim from the enlightened VMCS,\nwithout any bounds check, i.e. isn't guaranteed to be under the limit of\n4096.\n\nFailure to check the bounds of the VP ID leads to an out-of-bounds read\nwhen testing the sparse bank, and super strictly speaking could lead to KVM\nperforming an unnecessary TLB flush for an L2 vCPU.\n\n ==================================================================\n BUG: KASAN: use-after-free in hv_is_vp_in_sparse_set+0x85/0x100 [kvm]\n Read of size 8 at addr ffff88811ba5f598 by task hyperv_evmcs/2802\n\n CPU: 12 UID: 1000 PID: 2802 Comm: hyperv_evmcs Not tainted 7.1.0-rc2 #7 PREEMPT\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n Call Trace:\n <TASK>\n dump_stack_lvl+0x51/0x60\n print_report+0xcb/0x5d0\n kasan_report+0xb4/0xe0\n kasan_check_range+0x35/0x1b0\n hv_is_vp_in_sparse_set+0x85/0x100 [kvm]\n kvm_hv_flush_tlb+0xe9e/0x16c0 [kvm]\n kvm_hv_hypercall+0xe6b/0x1e60 [kvm]\n vmx_handle_exit+0x485/0x1b60 [kvm_intel]\n kvm_arch_vcpu_ioctl_run+0x22e3/0x5070 [kvm]\n kvm_vcpu_ioctl+0x5d0/0x10c0 [kvm]\n __x64_sys_ioctl+0x129/0x1a0\n do_syscall_64+0xb9/0xcf0\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n RIP: 0033:0x7f0e62d1a9bf\n </TASK>\n\n The buggy address belongs to the physical page:\n page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffffffffffffffff pfn:0x11ba5f\n flags: 0x4000000000000000(zone=1)\n raw: 4000000000000000 0000000000000000 00000000ffffffff 0000000000000000\n raw: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000000\n page dumped because: kasan: bad access detected\n\n Memory state around the buggy address:\n ffff88811ba5f480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n ffff88811ba5f500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n >ffff88811ba5f580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n ^\n ffff88811ba5f600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n ffff88811ba5f680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n ==================================================================\n Disabling lock debugging due to kernel taint\n\nOpportunistically add a compile time assertion to ensure the maximum number\nof sparse banks exactly matches the number of possible bits in the passed\nin mask.\n\n[sean: add KASAN splat, drop comment, add assert, massage changelog]"
}
],
"lastModified": "2026-08-17T05:17:22.977",
"configurations": [
{
"nodes": [
{
"negate": false,
"cpeMatch": [
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}