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CVE-2026-81012
platform/x86: hp-bioscfg: fix off-by-one write in hp_get_string_from_buffer()
Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem drivers/platform. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-81012 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
hp_get_string_from_buffer() clamps the converted string length against the destination buffer size with "size > dst_size", so when the converted length is exactly equal to dst_size, conv_dst_size is left at dst_size and the unconditional NUL terminator write dst[conv_dst_size] = 0; lands one byte past the destination buffer. This is the same shape of bug as the previously fixed off-by-one in hp_convert_hexstr_to_str(): the buffer is sized correctly for the content, but the terminator write is never checked against that size. Fix by changing the comparison to ">=" so conv_dst_size is always left with room for the terminator. All fixed-size destinations that reach this function (path[512], current_value[512], current_password/current_value[64], and the per-entry buffers in encodings[][512] and prerequisites[][512]) are affected.
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/platform/x86/hp/hp-bioscfg/bioscfg.c
- What this is
- HP BIOSCFG DRIVERMAINTAINERS section matched on drivers/platform/x86/hp/hp-bioscfg/ · platform-driver-x86@vger.kernel.org · Maintained
- Kernel module
- hp_bioscfg
Check it on the machine
grep -wE 'CONFIG_HP_BIOSCFG|CONFIG_X86|CONFIG_X86_PLATFORM_DRIVERS_HP' /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 hp_bioscfgPrints 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. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookworm?
- trixieMnot built on amd64/cloud-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, s390x/s390x
- forky, sidMnot built on amd64/cloud-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, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k
- ?
- not established - no Makefile entry for the affected file
- M
- a module where it is built at all; some flavours do not build it
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.
- Build switches
- CONFIG_HP_BIOSCFG, CONFIG_X86, CONFIG_X86_PLATFORM_DRIVERS_HP
- 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
- 2026-09-11 (37 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
- 0.14%, higher than 3.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/platform
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.6 | 6.6.157 | 8f5aa1506cdd |
| 6.6 | 6.12.109 | 3cc772d01547 |
| 6.6 | 6.18.50 | b15b334fbc3c |
| 6.6 | 7.2.4 | ddf98cf33529 |
| 6.6 | 7.3 | dc03f05e419f |
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
- hp_get_string_from_buffer() runs during local hp-bioscfg initialization while parsing HP WMI/ACPI BIOS attribute buffers from wmi_query_block(); there is no network, Bluetooth, or USB protocol path into this UTF-16 conversion.
- AC:LAttack complexity, low
- A WMI buffer whose converted string length equals the destination size deterministically writes the NUL terminator one byte past the buffer; firmware controls the length prefix and contents, with no race or attacker-uncontrollable layout required to trigger the overflow.
- PR:NPrivileges required, none
- The overflow executes automatically in hp_init()/hp_init_bios_attributes() while parsing firmware-supplied WMI buffers, with no Linux user account, capability, or sysfs check on that path; a supply-chain or compromised HP BIOS suffices.
- UI:NUser interaction, none
- Every WMI BIOS attribute instance is parsed automatically at boot or module load; exploitation does not require a victim to mount a filesystem, open a file, or take any other action.
- S:UScope, unchanged
- The out-of-bounds write corrupts kernel heap or stack in the same host kernel security authority and does not cross a VM, IOMMU, or sandbox boundary.
- C:HConfidentiality impact, high
- The one-byte overflow past heap objects (including a kcalloc buffer sized from the remaining WMI payload) and kernel-stack name buffers corrupts adjacent objects or pointer LSBs, which is leverageable for kernel memory disclosure.
- I:HIntegrity impact, high
- This is an out-of-bounds write past fixed-size fields and a separately allocated heap buffer whose size is chosen from the firmware buffer length, giving a slab-adjacent write primitive usable for control-flow hijacking after heap grooming.
- A:HAvailability impact, high
- Writing one byte past a kmalloc object or kernel stack buffer can corrupt adjacent pointers or slab metadata and cause a kernel oops, KASAN abort, or panic during hp-bioscfg bring-up.