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CVE-2026-89904
LoongArch: Fix acpi_package_ids[] array overflow
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem arch/loongarch. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-89904 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 | 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
With LoongArch virt machine, a typical setting is one core per socket, there will max 256 sockets (packages) on one VM. With PPTT acpi table, array acpi_package_ids[] will be overflowed. Here change the array size of acpi_package_ids[] with the max value of MAX_PACKAGES and KVM_MAX_VCPUS.
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/loongarch/kernel/acpi.c
- What this is
- LOONGARCHMAINTAINERS section matched on arch/loongarch/ · loongarch@lists.linux.dev · Maintained
Check it on the machine
grep -w CONFIG_ACPI /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.
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.
- bookwormYnot built on armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le
- trixieYnot built on armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
- forky, sidYnot built on armhf/armmp, armhf/armmp-lpae, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
- bookworm · linux-6.12Ynot built on armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k
- Y
- built in where it is built at all; some flavours do not build it
- Build switch
- CONFIG_ACPI
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
- 2026-09-16 (33 days ago)source
- CVSS
- 8.4 high
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/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
- unimportantsource
- Subsystem
- arch/loongarch
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.12.101 | 6.12.110 | 0195e04b1eec |
| 6.18.42 | 6.18.51 | d3fd094c13c6 |
| 7.2 | 7.2.5 | 6311b8c471af |
| 7.2 | 7.3 | 2a2367d46d7a |
| 7.1.6 | 0 | 0 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| 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
- The overflow is in parse_acpi_topology(), called from loongson_prepare_cpus() during smp_prepare_cpus() as the kernel consumes the firmware or VMM ACPI PPTT table at boot; there is no network, adjacent-network, or USB path into this parser.
- AC:LAttack complexity, low
- A LoongArch virt machine with the typical one-core-per-socket layout can expose up to 256 packages (KVM_MAX_VCPUS) against acpi_package_ids[MAX_PACKAGES] (16 entries); each new PPTT package ID is stored via acpi_package_ids[acpi_nr_packages++] with no bounds check, so the overflow is deterministic with no race.
- PR:NPrivileges required, none
- PPTT is parsed automatically during SMP bring-up with no capable() check, Linux login, or syscall. A hypervisor-generated virt-machine table or supply-chain/evil-maid firmware with more than 16 unique packages triggers the write without any account or user-namespace privilege.
- UI:NUser interaction, none
- The out-of-bounds write runs as part of ordinary kernel_init_freeable() SMP setup before userspace starts; no victim mount, file open, or other interactive action is required.
- S:UScope, unchanged
- The write corrupts kernel BSS and related globals inside the same kernel that parsed PPTT. This is not a KVM guest-to-host escape, sandbox breakout, or IOMMU/DMA authority crossing.
- C:HConfidentiality impact, high
- Firmware-controlled 32-bit topology IDs are written past acpi_package_ids[] into adjacent kernel BSS, and the later canonicalization loop also reads past the array. Per memory-corruption guidance that is High confidentiality, not a bounded few-byte leak.
- I:HIntegrity impact, high
- This is a direct out-of-bounds write of firmware-controlled ints past a 16-entry static array (up to hundreds of stores on large VMs). Out-of-bounds writes score High because they can smash adjacent BSS, including function pointers, and enable control-flow hijack.
- A:HAvailability impact, high
- Smashing kernel BSS during SMP bring-up can oops, panic, or prevent boot. Canonicalized package IDs >= MAX_PACKAGES also index loongson3_cpufreq's cpufreq_mutex[MAX_PACKAGES] out of bounds, causing further crashes.