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CVE-2026-89932
KVM: nVMX: Always flush vpid02 on first use
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem arch/x86. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-89932 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Make sure vpid02 is always flushed on first use by setting last_vpid=0 when allocating vpid02. nested_vmx_transition_tlb_flush() will always detect a VPID change on first VM-Enter after VMXON, because VPID=0 in vmcs12 is not allowed if L1 enables VPID. This avoids using stale TLB entries from a previous lifetime of the VPID, that might have been associated with a different vCPU (or a completely different VM). Note that last_vpid is already being initialized as 0 when the vCPU is created, but it is not reset when vpid02 is freed on VMXOFF. Hence, the problem can only occur if L1 does VMXOFF -> VMXON, runs an L2, and KVM happens to reuse a VPID that has TLB entries on the physical CPU.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
arch/x86/kvm/vmx/nested.c
- What this is
- KERNEL VIRTUAL MACHINE FOR X86 (KVM/x86)MAINTAINERS section matched on arch/x86/kvm/*/ · kvm@vger.kernel.org · Supported
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid, bookworm · linux-6.12?
- ?
- not established - no Makefile entry for the affected file
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS
Signals
- Published
- 2026-09-16 (33 days ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.16%, higher than 5.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- arch/x86
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.4 | 5.15.221 | 26de0d2d9a8d |
| 4.4 | 6.1.188 | 8bc609999ec2 |
| 4.4 | 6.6.157 | 62604376c313 |
| 4.4 | 6.12.110 | 8b98d662ab24 |
| 4.4 | 6.18.51 | 22dfcc22c95e |
| 4.4 | 7.2.5 | 121991d15073 |
| 4.4 | 7.3 | f0772389413d |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- Reached when an L1 nested-VMX guest executes VMXOFF then VMXON and VMLAUNCH/VMRESUME on the host KVM_RUN path (handle_vmxon/enter_vmx_operation into nested_vmx_transition_tlb_flush); no network, adjacent-radio, or physical path hits nVMX VPID allocation.
- AC:LAttack complexity, low
- The L1 attacker fully controls VMXOFF, VMXON, vmcs12 VPID, and vCPU pinning; allocate_vpid() is a deterministic global bitmap, nested VMX and VPID are default, and skipping last_vpid=0 makes the omitted INVVPID on first VM-Enter after VMXON reliably hit.
- PR:LPrivileges required, low
- Needs /dev/kvm and nested VMX, typically a kvm-group user or cloud tenant running QEMU, not init-namespace root; handle_vmxon() only checks guest CPL=0 and CR4.VMXE, and KVM create/run ioctls have no CAP_SYS_ADMIN gate.
- UI:NUser interaction, none
- Once the attacker has a nested-capable VM, they trigger the flaw with their own VMXOFF/VMXON and VMLAUNCH; no separate victim action such as attaching a device or mounting a filesystem is required.
- S:CScope, changed
- Skipping the vpid02 INVVPID lets L2 use stale hardware TLB entries from a previous lifetime of that VPID, including another vCPU or a different VM, crossing KVM guest isolation so impact is outside L1's security authority.
- C:HConfidentiality impact, high
- Reused vpid02 linear or combined TLB entries can translate L2 loads onto another VM's or recycled host physical pages, giving a read primitive over co-resident guest memory rather than a bounded pointer leak.
- I:HIntegrity impact, high
- The same stale translations apply to stores, so L2 can write through another VM's cached GPA/HPA mappings, corrupting co-resident guest memory and enabling control-flow hijack in the victim VM or further host compromise if pages were reused.
- A:HAvailability impact, high
- Stale VPID hits produce wrong translations that surface as KVM internal/emulation failures and can oops or panic the host when walks land on recycled or unmapped host pages, denying service to the hypervisor and co-located VMs.