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CVE-2026-89912
KVM: arm64: vgic-its: Don't dereference a NULL collection on ITT save
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem arch/arm64. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-89912 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixedDSA-6568-1 · 2026-10-16 · text | 6.12.113-1 | Update the kernel and reboot. DSA-6568-1 shipped the fix on 2026-10-16, in 6.12.113-1. 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. |
The vulnerability
What the bug is
MAPC with V=0 drops ite->collection but leaves the ITE on the device's ITT list, and vgic_its_save_ite() dereferences it unconditionally. A guest that issues MAPD, MAPTI and then MAPC(V=0) therefore oopses the host when the VMM issues KVM_DEV_ARM_ITS_SAVE_TABLES to migrate it. That sequence is UNPREDICTABLE per the architecture, but KVM already handles the resulting state in the translate, MOVI and DISCARD paths. Save a zeroed entry, which vgic_its_restore_ite() reads back as invalid. Skipping the ITE instead would leave the ITT slot holding whatever is in guest memory, and restore rejects an entry naming a collection the restored collection table does not have.
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/arm64/kvm/vgic/vgic-its.c
- What this is
- KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)MAINTAINERS section matched on arch/arm64/kvm/ · linux-arm-kernel@lists.infradead.org · Maintained
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?
- ?
- 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
- 7.1 high
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.19%, higher than 7.6% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- arch/arm64
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.12 | 6.12.113 | 2c3a87ad3d39 |
| 4.12 | 6.18.51 | 3d4c26b16a04 |
| 4.12 | 7.2.5 | 36df368861d2 |
| 4.12 | 7.3 | c6c156d931c3 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DSA-6568-1 | 2026-10-16 | trixie 6.12.113-1 | 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 NULL dereference is reached only via the local KVM ioctl KVM_SET_DEVICE_ATTR(KVM_DEV_ARM_ITS_SAVE_TABLES) after the guest programs in-kernel GICv3 ITS MMIO (MAPD/MAPTI/MAPC or GITS_BASER); it is not triggered by network packets, adjacent-radio frames, or a physical device.
- AC:LAttack complexity, low
- A guest can deterministically issue MAPD, MAPTI, then MAPC with V=0, or clear GITS_BASER collection Valid, leaving ITEs on the ITT with a NULL collection; SAVE_TABLES then always dereferences it with no race or attacker-uncontrollable host layout.
- PR:NPrivileges required, none
- The highest-impact case is a cloud VM tenant who needs no host privileges: they program the ITS from guest EL1 and the host oopses when the hypervisor saves ITS tables during automated live migration, without host root, capabilities, or tenant access to /dev/kvm.
- UI:NUser interaction, none
- No extra victim action is required beyond normal hypervisor operations such as automated live migration or snapshot save that invoke SAVE_TABLES; a local VMM can also issue that ioctl itself.
- S:CScope, changed
- The fault runs in host KVM while saving guest-controlled ITS state, so a host oops/panic takes down the hypervisor and co-resident VMs, crossing the KVM guest-to-host security boundary.
- C:NConfidentiality impact, none
- vgic_its_save_ite() only loads collection_id through a NULL ite->collection pointer; this is a pure NULL dereference with no out-of-bounds read, use-after-free, or other host disclosure primitive.
- I:NIntegrity impact, none
- The NULL collection is read and not written, and the bug does not corrupt host kernel memory, provide an arbitrary write, or hijack host control flow beyond the faulting load.
- A:HAvailability impact, high
- Dereferencing the NULL collection in vgic_its_save_ite() oopses or panics the host kernel during ITS table save, denying service to the hypervisor and every co-located VM.