CVE-2026-64247

Host memory disclosure via unchecked sparse bank index

Published Jul 24, 2026 · Updated Jul 24, 2026

Out-of-bounds read in Linux Kernel KVM Hyper-V support allows guest OS users to disclose host memory through an L2 TLB flush. The hv_is_vp_in_sparse_set function uses a VP ID copied verbatim from the enlightened VMCS to index sparse_banks without enforcing the 4,096-ID maximum. Exploitation requires a nested Hyper-V guest or low-privileged access to /dev/kvm; the read crosses the guest-host boundary, and a false membership result can cause an unnecessary L2 vCPU flush.

CVSS severity7.1
High
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Linux Kernel KVM Hyper-V support allows guest OS users to disclose host memory through an L2 TLB flush. The hv_is_vp_in_sparse_set function uses a VP ID copied verbatim from the enlightened VMCS to index sparse_banks without enforcing the 4,096-ID maximum. Exploitation requires a nested Hyper-V guest or low-privileged access to /dev/kvm; the read crosses the guest-host boundary, and a false membership result can cause an unnecessary L2 vCPU flush.

The record

CVE
CVE-2026-64247
Published
Jul 24, 2026
Updated
Jul 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-125
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.2
  2. Affected versionversion=c58a318f6090efe06e6702b8882e2026f44f620e <4721f8160f17554b003e8928bb61e6c9b2fe92a3
  3. Affected versionversion=c58a318f6090efe06e6702b8882e2026f44f620e <83c2f52c6a78b1590034e955cff3fe0b052fe4ae
  4. Affected versionversion=c58a318f6090efe06e6702b8882e2026f44f620e <d18756b12aab30d07794446445c93112e5c69a2e
  5. Affected versionversion=c58a318f6090efe06e6702b8882e2026f44f620e <e36095d8d922bb26ce860231aacf0cd14edea07c
  6. Affected versionversion=c58a318f6090efe06e6702b8882e2026f44f620e <f636cf6a1e7b7f40d48d8d08bd5f152aa61dd130

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.2; version=c58a318f6090efe06e6702b8882e2026f44f620e <4721f8160f17554b003e8928bb61e6c9b2fe92a3; version=c58a318f6090efe06e6702b8882e2026f44f620e <83c2f52c6a78b1590034e955cff3fe0b052fe4ae; version=c58a318f6090efe06e6702b8882e2026f44f620e <d18756b12aab30d07794446445c93112e5c69a2e; version=c58a318f6090efe06e6702b8882e2026f44f620e <e36095d8d922bb26ce860231aacf0cd14edea07c; version=c58a318f6090efe06e6702b8882e2026f44f620e <f636cf6a1e7b7f40d48d8d08bd5f152aa61dd130

Published CVSS scores

7.1Linux kernelCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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