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CVE-2026-72283
KVM: x86: Nullify irqfd->producer if updating IRTE for bypass fails
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem arch/x86. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-72283 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Nullify irqfd->producer if updating the IRTE for bypass fails, as leaving a dangling pointer will result in a use-after-free if the irqfd is reachable through KVM's routing, but the producer is freed separately. E.g. for VFIO PCI, the producer is embedded in struct "vfio_pci_irq_ctx" and freed when the vector is disabled, which can happen independent of routing updates. [sean: drop PPC change, massage changelog]
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/irq.c
- What this is
- KERNEL VIRTUAL MACHINE FOR X86 (KVM/x86)MAINTAINERS section matched on arch/x86/kvm/ · kvm@vger.kernel.org · Supported
- Kernel module
- kvm
Check it on the machine
grep -wE 'CONFIG_KVM|CONFIG_KVM_X86' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w kvmPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormBnot built on arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp
- trixieMnot built on arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- B
- built in on some, a module on others, absent on the rest
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_KVM, CONFIG_KVM_X86
- Reads as
- all on means the file is compiled; any one off means it is not.
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 kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-15 (2 months 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
- 0.18%, higher than 7.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- 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 |
|---|---|---|
| 6.17 | 6.18.40 | d1379888cc42 |
| 6.17 | 7.1.5 | d5560b6569cd |
| 6.17 | 7.2 | ed446e8aa894 |
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
- The bug is reached only through local KVM VM ioctls (KVM_IRQFD, KVM_SET_GSI_ROUTING) and VFIO PCI IRQ ioctls that wire an irqfd consumer to a VFIO MSI/MSI-X producer; there is no network, adjacent-radio, or physical-device attack surface.
- AC:LAttack complexity, low
- An attacker who can open the VM and VFIO fds controls both sides of the failure window (provoke kvm_pi_update_irte() to fail during irq_bypass_add_producer, disable the VFIO vector to free vfio_pci_irq_ctx, then change GSI routing) and can retry routing/affinity until the dangling irqfd->producer is dereferenced.
- PR:LPrivileges required, low
- Exploitation requires only local access to KVM and VFIO device nodes to issue the relevant ioctls (typical for QEMU/libvirt kvm-group operators or cloud tenants running VMs with PCI passthrough), not full init-namespace root or capabilities obtainable only inside unprivileged user namespaces.
- UI:NUser interaction, none
- The use-after-free is triggered entirely by the attacker's own ioctl sequence and subsequent routing updates; no victim login, file open, mount, or other interactive action is required.
- S:CScope, changed
- The dangling producer is used to update IOMMU posted-interrupt IRTEs for VFIO-assigned PCI MSIs, crossing the guest/host device-assignment boundary; corrupting interrupt remapping can compromise the host kernel and enable VM escape rather than staying within the attacker's VM scope.
- C:HConfidentiality impact, high
- This is a kernel heap use-after-free on irqfd->producer embedded in vfio_pci_irq_ctx; freed-object reuse supplies attacker-influenced host_irq values to irq_set_vcpu_affinity(), enabling arbitrary kernel memory reads and pointer disclosure, not merely a bounded leak.
- I:HIntegrity impact, high
- UAF of the VFIO irq producer plus mistaken irq_set_vcpu_affinity()/IRTE reprogramming with a stale or attacker-controlled IRQ number can corrupt host kernel heap metadata and IOMMU interrupt tables, providing a path to arbitrary write and code execution.
- A:HAvailability impact, high
- Dereferencing the freed vfio_pci_irq_ctx from kvm_pi_update_irte() during kvm_irq_routing_update() can immediately BUG/WARN/oops the host kernel; even attempted exploitation of the UAF commonly crashes the host.