Vulnerability in Kernel (CVE-2026-23402)
Summary
Vulnerability in Kernel (CVE-2026-23402). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.18.21, 6.19.11 or later.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
KVM: x86/mmu: Only WARN in direct MMUs when overwriting shadow-present SPTE
Adjust KVM's sanity check against overwriting a shadow-present SPTE with a
another SPTE with a different target PFN to only apply to direct MMUs,
i.e. only to MMUs without shadowed gPTEs. While it's impossible for KVM
to overwrite a shadow-present SPTE in response to a guest write, writes
from outside the scope of KVM, e.g. from host userspace, aren't detected
by KVM's write tracking and so can break KVM's shadow paging rules.
------------[ cut here ]------------
pfn != spte_to_pfn(*sptep)
WARNING: arch/x86/kvm/mmu/mmu.c:3069 at mmu_set_spte+0x1e4/0x440 [kvm], CPU#0: vmx_ept_stale_r/872
Modules linked in: kvm_intel kvm irqbypass
CPU: 0 UID: 1000 PID: 872 Comm: vmx_ept_stale_r Not tainted 7.0.0-rc2-eafebd2d2ab0-sink-vm #319 PREEMPT
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:mmu_set_spte+0x1e4/0x440 [kvm]
Call Trace:
ept_page_fault+0x535/0x7f0 [kvm]
kvm_mmu_do_page_fault+0xee/0x1f0 [kvm]
kvm_mmu_page_fault+0x8d/0x620 [kvm]
vmx_handle_exit+0x18c/0x5a0 [kvm_intel]
kvm_arch_vcpu_ioctl_run+0xc55/0x1c20 [kvm]
kvm_vcpu_ioctl+0x2d5/0x980 [kvm]
__x64_sys_ioctl+0x8a/0xd0
do_syscall_64+0xb5/0x730
entry_SYSCALL_64_after_hwframe+0x4b/0x53
---[ end trace 0000000000000000 ]---
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-2026-23402 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.18.21, 6.19.11 or later.
If unsure, ask your IT team or search "Kernel CVE-2026-23402" on the vendor's site.
CVE-2026-23402 (Kernel)
Patched: 6.18.21, 6.19.11 — apply immediately
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.
A vulnerability (unclassified) exists in Kernel.
Check the vendor advisory for the affected versions of Kernel.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 6.18.21, 6.19.11.
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. Run grep -r 'Kernel' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'Kernel' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Kernelを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Kernel to 6.18.21, 6.19.11ステージング環境で 6.18.21, 6.19.11 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-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-2026-23402 linux-lts Fixed in: 6.18.35-r1
- Debian DEBIAN-CVE-2026-23402 linux Fixed in: 6.19.11-1
- Ubuntu UBUNTU-CVE-2026-23402 linux-hwe-edge
References
- advisory github.com
- advisory nvd.nist.gov
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org