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CVE-2026-99176— KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry

Quick assessment

Affected

Linux Linux

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，以下漏洞已得到修复： KVM: nVMX：若在非 VM-Entry 场景下加载 L2 状态失败，则将 MMU 重置回根 MMU 当在非"VM-Entry"场景（即模拟 RSM 指令或处理时）加载 L2 状态失败的情况下，需将 vCPU 的 MMU 指针重置回根 MMU。若未能正确回退该 MMU 指针，会导致 KVM 尝试使用嵌套 MMU 运行 L1 虚拟机，这一问题在 vCPU 于虚拟机崩溃前释放其嵌套状态时尤为严重。构建嵌套 EPT MMU 的根结构需经过，而该结构在启用或禁用 nVM

AI Predicted 7.8 Difficulty: Moderate Updated Oct 28, 2026

Possible ATT&CK Techniques 2 AI

T1068.001 T1068.003

Affected Version Matrix 8

Vendor	Product	Version Range	Status
Linux	Linux	`72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778< d00d5f534a8238674755e59826a6c7d3c8efb870`	affected
		`72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778< c9716f956216eb74ab0aad7f633586edd49e0322`	affected
		`72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778< c8f4cfe1cf93bce924e27f2abead7a4c4a487505`	affected
		`4.15`	affected
		`< 4.15`	unaffected
		`6.18.59≤ 6.18.*`	unaffected
		`7.2.13≤ 7.2.*`	unaffected
		`7.3≤ *`	unaffected

Updated Oct 28, 2026

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Vulnerability Information

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Vulnerability Title

KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry

Source: CVE Program / CVE List V5

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry Reset the vCPU's MMU pointer back to the root MMU if loading L2 state fails in the "not from VM-Entry" case, i.e. when emulating RSM or handling KVM_SET_NESTED_STATE. Failure to unwind the MMU pointer results in KVM trying to run L1 with a nested MMU, and is especially problematic if the vCPU manages to free its nested state before the VM crashes. Constructing the root for a nested EPT MMU goes through vmcs12, which is dynamically allocated/freed when nVMX is enabled/disabled. And so if the nested state is freed with the MMU still pointing at the nested MMU, KVM will hit a NULL pointer deref when attempting to get L1=>L2 EPTP. BUG: kernel NULL pointer dereference, address: 0000000000000078 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 114a2d067 P4D 111743067 PUD 11141f067 PMD 0 Oops: Oops: 0000 [#1] SMP CPU: 20 UID: 1000 PID: 1272 Comm: nested_tdp_faul Not tainted 7.3.0-rc4-8c89f11d1a99b-sink-vm #1914 PREEMPTLAZY Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel] Call Trace: <TASK> kvm_mmu_load+0xcd/0x870 [kvm] kvm_arch_vcpu_ioctl_run+0x18f5/0x1f80 [kvm] kvm_vcpu_ioctl+0x2c7/0x970 [kvm] __x64_sys_ioctl+0x90/0xd0 do_syscall_64+0x9c/0x4d0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x47491b </TASK> Modules linked in: kvm_intel kvm irqbypass CR2: 0000000000000078 ---[ end trace 0000000000000000 ]--- RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel] [sean: write changelog]

Source: CVE Program / CVE List V5

CVSS Information

N/A

Source: CVE Program / CVE List V5

Vulnerability Type

N/A

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
Linux	Linux	72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778 ~ d00d5f534a8238674755e59826a6c7d3c8efb870	-
Linux	Linux	4.15	-

II. Public POCs for CVE-2026-99176

#	POC Description	Source Link	Shenlong Link

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III. Intelligence Information for CVE-2026-99176

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Patches & Fixes for CVE-2026-99176 (2)

https://www.cve.org/CVERecord?id=CVE-2026-99176

Same Patch Batch · Linux · 2026-10-28 · 117 CVEs total

CVE-2026-99143		tracing: Keep the predicate limit separate from program capacity
CVE-2026-99129		selinux: fix BPF token permission checks
CVE-2026-99130		io_uring/cancel: don't spin on local work the task can't run
CVE-2026-99131		xfs: fix capability check in xfs
CVE-2026-99133		net/iucv: fix the recvmsg window update
CVE-2026-99132		xfs: don't hold buffer locks across sync transaction commit in xfs_sync_sb_buf
CVE-2026-99134		mac802154: fix data race and NULL deref on local->assoc_dev
CVE-2026-99135		dm-integrity: fix infinite loop on discard with large tag size
CVE-2026-99137		cifs: don't update i_size in cifs_do_truncate without a cached handle
CVE-2026-99136		dm-crypt: fix a tiny race condition in crypt_dec_pending
CVE-2026-99138		tcp: fix use-after-free in do_tcp_getsockopt(TCP_CC_INFO)
CVE-2026-99140		tracing: Fix hist trigger timestamps for buffered events
CVE-2026-99139		tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)
CVE-2026-99141		tracing: Fix crash in print_graph_function_event()
CVE-2026-99142		tracing: Check operator stack capacity before pushing
CVE-2026-99154		scsi: libiscsi: Reject a negative task index from parse_pdu_itt
CVE-2026-99151		drm/amd/display: Fix NULL sink dereference in USB4 bandwidth functions
CVE-2026-99153		scsi: libiscsi: Validate the ITT reflected in a Reject PDU
CVE-2026-99152		scsi: libiscsi: Validate the task named by a management response
CVE-2026-99150		drm/amdgpu: don't drop the runtime PM reference twice in amdgpu_gpr

Showing top 20 of 117 CVEs. View all on vendor page → →

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