Out-of-Bounds Read in Linux kernel (CVE-2026-64247)
Summary
Vulnerability in Linux kernel (CVE-2026-64247). Confidential information can be exposed externally.
Original description
The description as published by the source.
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.
==================================================================
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:
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_s…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-64247 has been found in Linux kernel.
Confidential information can be exposed externally. CVSS score: 8.4/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-64247" on the vendor's site.
CVE-2026-64247 (Linux kernel) — CWE-125 / CVSS v3 8.4
Attack vector: local / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Out-of-bounds read (CWE-125) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: High (CVSS 8.4/10). Confidential information can be exposed externally.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-64247 linux-lts Fixed in: 6.12.95-r0
- Debian DEBIAN-CVE-2026-64247 linux Fixed in: 6.12.95-1
- Ubuntu UBUNTU-CVE-2026-64247 linux-hwe-edge
References
- advisory nvd.nist.gov
- advisory github.com
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web github.com