EUVD-2026-17830
GHSA-r3ww-97x6-6h4v
Lifecycle Timeline
4Description
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: <TASK> 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 </TASK> ---[ end trace 0000000000000000 ]---
Analysis
Linux kernel KVM x86/mmu module improperly validates shadow page table entries (SPTEs) in indirect MMUs, allowing host userspace writes to bypass KVM's write-tracking detection and corrupt shadow paging state. The vulnerability affects KVM implementations on x86 systems with nested or indirect MMU configurations where writes originating outside KVM's scope (e.g., from host userspace via memory access) are not detected, potentially leading to memory corruption or VM escape. …
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Priority Score
Vendor Status
Debian
| Release | Status | Fixed Version | Urgency |
|---|---|---|---|
| bullseye | not-affected | - | - |
| bullseye (security) | fixed | 5.10.251-1 | - |
| bookworm | not-affected | - | - |
| bookworm (security) | fixed | 6.1.164-1 | - |
| trixie | not-affected | - | - |
| trixie (security) | fixed | 6.12.74-2 | - |
| forky | vulnerable | 6.19.8-1 | - |
| sid | vulnerable | 6.19.10-1 | - |
| (unstable) | fixed | (unfixed) | - |
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External POC / Exploit Code
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