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CVE-2026-80684
KVM: s390: pci: Fix NULL dereference on AIBV allocation failure
Published 2026-08-28 (2 months ago) by the Linux kernel CNA. Subsystem arch/s390. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-80684 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-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.105-1 | Update the kernel and reboot. Fixed in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The airq_iv_create() can return NULL on failure, but the return value was never checked. If it fails, zdev->aibv will be NULL and fail when dereferenced in kvm_zpci_set_airq(). Add a NULL check and free the previously allocated AISB bit and zdev->aisb on failure.
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/s390/kvm/pci.c
- What this is
- S390 VFIO-PCI DRIVERMAINTAINERS section matched on arch/s390/kvm/pci* · linux-s390@vger.kernel.org · Supported
- Kernel module
- kvm
Check it on the machine
grep -wE 'CONFIG_KVM|CONFIG_VFIO_PCI_ZDEV_KVM' /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 does not build this code in 2 releases. It does build it in 3 releases, so the answer depends on which release the machine runs.
- bookwormn
- trixieMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, 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
- forky, sidMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, 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
- bookworm · linux-6.12n
- n
- not enabled on any flavour - this release does not build the code
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_KVM, CONFIG_VFIO_PCI_ZDEV_KVM
- 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
- 2026-08-28 (2 months ago)source
- CVSS
- 9.3 critical
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.20%, higher than 8.6% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- arch/s390
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.0 | 6.1.183 | 96099486b639 |
| 6.0 | 6.6.151 | 0a95abe96440 |
| 6.0 | 6.12.103 | df947d85e164 |
| 6.0 | 6.18.44 | e137d082325b |
| 6.0 | 7.1.8 | d1a103dc9016 |
| 6.0 | 7.2 | 8bf09b9b7d32 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | 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
- The bug is reached through the KVM_S390_ZPCI_OP VM ioctl (kvm_arch_vm_ioctl -> kvm_s390_pci_zpci_op -> kvm_s390_pci_aif_enable), a local syscall on the s390 hypervisor host, not via any network-facing kernel service.
- AC:LAttack complexity, low
- An attacker can reliably trigger airq_iv_create() failure and the subsequent NULL dereference by issuing KVM_S390_ZPCIOP_REG_AEN under controlled host memory pressure or repeated registration attempts while holding a valid passthrough zPCI device context.
- PR:NPrivileges required, none
- A malicious KVM guest with an assigned VFIO zPCI passthrough device can cause QEMU to issue KVM_S390_ZPCIOP_REG_AEN during normal adapter-event setup without possessing any host-root or init-namespace administrative credentials.
- UI:NUser interaction, none
- Exploitation requires no action by a separate victim user; triggering occurs through the attacker's own guest workload or VMM issuing the REG_AEN ioctl during standard zPCI passthrough interrupt-forwarding registration.
- S:CScope, changed
- The vulnerable KVM host code executes on behalf of a guest's passthrough device setup, and the resulting host kernel crash or corrupted global AIFT/GAIT interrupt-forwarding state impacts the hypervisor and resources outside the attacking guest's security boundary.
- C:HConfidentiality impact, high
- Before the NULL dereference, unchecked allocation failure still populates host GAIT/summary-bit tables with attacker-influenced interrupt-routing fields, enabling misdelivery or exposure of adapter events intended for other guests or host contexts.
- I:HIntegrity impact, high
- Failed AIBV allocation leaves partially written host kernel interrupt-forwarding metadata (GAIT entries, kzdev pointers, summary-bit assignments) under attacker-controlled ioctl parameters, constituting exploitable kernel memory corruption prior to the crash.
- A:HAvailability impact, high
- When zdev->aibv is NULL, kvm_zpci_set_airq() dereferences zdev->aibv->vector and airq_iv_end(zdev->aibv), causing a host kernel oops/panic that denies availability to all VMs on the system.