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CVE-2026-81006
ipmi: Remove all sysfs files on registration failure
Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem drivers/char. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-81006 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 | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| 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
ipmi_add_smi() creates the nr_users and nr_msgs files before trying to create the maintenance_mode file. If that last creation fails, the error path removes only nr_users before dropping the final reference to the interface. Remove nr_msgs as well so no sysfs attribute embedded in the freed interface remains registered.
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/char/ipmi/ipmi_msghandler.c
- What this is
- IPMI SUBSYSTEMMAINTAINERS section matched on drivers/char/ipmi/ · openipmi-developer@lists.sourceforge.net · Supported
- Kernel module
- ipmi_msghandler
Check it on the machine
grep -w CONFIG_IPMI_HANDLER /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 ipmi_msghandlerPrints 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.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp
- trixieMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, riscv64/riscv64, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_IPMI_HANDLER
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
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.13%, higher than 2.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/char
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.18 | 6.18.50 | d46c97eddcbc |
| 6.18 | 7.2.4 | b115b7d06f26 |
| 6.18 | 7.3 | b6c46ab0bdee |
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
- ipmi_add_smi() is reached only from local host-side SMI probe (ipmi_si, ipmi_ssif, ipmi_ipmb, ipmi_powernv) and the dangling nr_msgs file is hit by local sysfs read(2); IPMI-over-LAN is BMC firmware and does not enter this kernel path.
- AC:LAttack complexity, low
- A local attacker can force device_create_file(maintenance_mode) to fail after nr_msgs is installed (memory pressure, hotmod/bind retries), then every read of the leftover attribute is a deterministic use-after-free with no race the attacker cannot control.
- PR:LPrivileges required, low
- DEVICE_ATTR_RO(nr_msgs) is mode 0444 and nr_msgs_show() has no capability check, so any unprivileged local user who can read sysfs can trigger the UAF after a failed SMI registration; this is not limited to init-namespace root and is not a pre-auth network path.
- UI:NUser interaction, none
- The attacker causes SMI registration failure and then reads the leftover nr_msgs sysfs file themselves; no separate victim action such as mounting a filesystem or opening a hostile file is required.
- S:UScope, unchanged
- The use-after-free is of host-kernel struct ipmi_smi and its embedded device_attribute; impact stays in the same kernel security authority with no VM, IOMMU, or sandbox boundary crossing.
- C:HConfidentiality impact, high
- The leftover sysfs attribute is embedded in the kmalloc'd ipmi_smi that intf_free() kfree()s, so nr_msgs_show() container_of() and the users-list walk are a slab use-after-free that can be reclaimed for arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- sysfs dispatches through device_attribute.show stored in the freed ipmi_smi, and nr_msgs_show() takes users_mutex and walks intf->users on that object, enabling heap spray and control-flow hijack per kernel UAF guidance.
- A:HAvailability impact, high
- Reading the dangling nr_msgs file dereferences freed ipmi_smi memory (mutex_lock and list traversal) and readily oopses or panics the kernel; any use-after-free is High availability impact even without full exploitation.