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CVE-2026-89997
dm: fix resume-vs-remove race
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem drivers/md. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-89997 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
If the user issues the resume ioctl and the remove ioctl at the same time, it may be possible that the device is resumed after it is suspended in __dm_destroy. The result is that the table is destroyed without calling the postsuspend method. Dm targets expect that they may be removed only after the postsuspend method method was called. If we break this expectation, it can cause misbehavior in various targets. For example - in the dm-integrity target, the reboot notifier is not unregistered, leading to use-after-free. Fix this bug by refusing to resume if the device is being destroyed.
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/md/dm.c
- What this is
- DEVICE-MAPPER (LVM)MAINTAINERS section matched on drivers/md/dm* · dm-devel@lists.linux.dev · Maintained
- Kernel module
- dm_mod
Check it on the machine
grep -wE 'CONFIG_BLK_DEV_DM|CONFIG_MD' /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 dm_modPrints 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 as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sid, bookworm · linux-6.12m
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switches
- CONFIG_BLK_DEV_DM, CONFIG_MD
- 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
- 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
- 0.16%, higher than 5.2% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/md
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.36 | 5.10.270 | 9757367bcf1d |
| 2.6.36 | 5.15.221 | 1ede2bce2bd6 |
| 2.6.36 | 6.1.188 | 3f04e6520d9a |
| 2.6.36 | 6.6.157 | 94f3d399c1dd |
| 2.6.36 | 6.12.110 | 3b59530b14fd |
| 2.6.36 | 6.18.51 | 36177beff2a9 |
| 2.6.36 | 7.2.5 | 94380ecd5ff9 |
| 2.6.36 | 7.3 | 44b43ec132f1 |
| 2.6.35.4 | 0 | 0 |
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 bug is reached only through local device-mapper ioctls on /dev/mapper/control (ctl_ioctl → DM_DEV_SUSPEND resume and DM_DEV_REMOVE → dm_resume racing __dm_destroy). No network, Bluetooth, or physical-bus path feeds this race.
- AC:LAttack complexity, low
- The attacker issues concurrent resume and remove ioctls on a mapped device they control, owning both sides of the race. __dm_destroy waits for holders while resume already holds a reference, so the window is reliably hit without victim state or an uncontrolled memory layout.
- PR:LPrivileges required, low
- ctl_ioctl requires capable(CAP_SYS_ADMIN). In the most severe reasonable deployment that capability is held by a container, CSI, or LVM/storage-stack administrator with delegated /dev/mapper/control rather than exclusive host root, matching kernel-CNA scoring of other device-mapper ioctl bugs as Low.
- UI:NUser interaction, none
- The attacker performs every step with its own ioctls (create and optionally suspend the mapped device, then concurrent resume and remove). No separate victim action such as mounting a filesystem or opening a file is required.
- S:UScope, unchanged
- The use-after-free and resulting kernel corruption stay inside the host kernel's security authority. This is standard kernel memory corruption, not a VM, IOMMU, or sandbox boundary crossing.
- C:HConfidentiality impact, high
- Skipping postsuspend after resume leaves target objects live after dtr frees them, including the dm-integrity reboot notifier and the dm-snapshot origin list. That use-after-free lets an attacker reclaim the object and obtain an arbitrary kernel read.
- I:HIntegrity impact, high
- The same use-after-free (global origin-list entry, reboot notifier, and restarted dm-thin/dm-cache work) is kernel memory corruption that can be turned into an arbitrary write and control-flow hijack, not merely on-disk integrity loss.
- A:HAvailability impact, high
- Use-after-free of target private data, list corruption on _dm_origins, and BUG_ON in dm_integrity_dtr when I/O remains in-progress cause a kernel oops, panic, or hang.