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CVE-2026-89992
cpuidle: dt_idle_genpd: kfree() the original name allocation
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem drivers/cpuidle. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-89992 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
dt_idle_pd_alloc() kasprintf()s the full node path, then points pd->name at kbasename() of that string. dt_idle_pd_free() kfree()s pd->name, which is no longer the start of the allocation. Copy the basename instead.
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.
drivers/cpuidle/dt_idle_genpd.c
- What this is
- CPUIDLE DRIVER - DT IDLE PM DOMAINMAINTAINERS section matched on drivers/cpuidle/dt_idle_genpd.c · linux-pm@vger.kernel.org · Supported
Check it on the machine
grep -wE 'CONFIG_CPU_IDLE|CONFIG_DT_IDLE_GENPD' /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 amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, i386/686-pae, i386/rt/686-pae, ppc64el/powerpc64le
- trixieYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
- forky, sidYnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
- bookworm · linux-6.12Ynot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, 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 switches
- CONFIG_CPU_IDLE, CONFIG_DT_IDLE_GENPD
- 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
- 2026-09-16 (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
- 0.18%, higher than 7.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/cpuidle
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.18 | 6.1.188 | 1312ae33b914 |
| 5.18 | 6.6.157 | a38caa9ed0d5 |
| 5.18 | 6.12.110 | 09d002c8fb02 |
| 5.18 | 6.18.51 | b519dfce1998 |
| 5.18 | 7.2.5 | 3394c7ba2333 |
| 5.18 | 7.3 | 2b0ac85512b7 |
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
- The invalid free is reached only from local PSCI and RISC-V SBI CPU idle genpd bring-up (psci_cpuidle_domain_probe and sbi_genpd_probe calling dt_idle_pd_alloc/dt_idle_pd_free) on ARM phones, automotive, and RISC-V boards; no network, Bluetooth, or USB receive path calls this code.
- AC:LAttack complexity, low
- After dt_idle_pd_alloc() succeeds, pd->name is an interior kbasename() pointer into the kasprintf() buffer; any later psci_pd_init/sbi_pd_init unwind (ENOMEM from genpd_alloc_data or pd_provider, or of_genpd_add_provider_simple failure) deterministically kfree()s that pointer, with no race or layout lottery.
- PR:NPrivileges required, none
- Both callers are builtin initcalls (core_initcall/arch_initcall) whose platform probe runs automatically on hierarchical CPU idle DT with no capability or credential check, so a Linux account is not required to reach the vulnerable unwind.
- UI:NUser interaction, none
- Probe and error unwind run during kernel initialization and deferred-probe retries; no victim needs to mount a filesystem, open a device, or load a module.
- S:UScope, unchanged
- The interior-pointer kfree corrupts host kernel SLUB state within the same security authority and does not escape a VM, bypass IOMMU, or cross another sandbox boundary.
- C:HConfidentiality impact, high
- kfree() of an interior kasprintf() pointer is an invalid free that corrupts slab metadata and overlapping objects; that memory-corruption primitive can be groomed into arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- SLUB treats the misaligned interior address as an object and corrupts the freelist; heap grooming can produce overlapping allocations and write primitives enabling control-flow hijack, matching this CNA's invalid-free scoring.
- A:HAvailability impact, high
- Debug and KASAN builds oops on the invalid free, and without them the corrupted slab commonly panics during CPU idle genpd bring-up, so availability impact is a kernel crash.