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CVE-2026-53400
i2c: core: fix adapter registration race
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem drivers/i2c. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-53400 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-4720-1 · 2026-08-05 · text | 6.1.180-1 | Update the kernel and reboot. DLA-4720-1 shipped the fix on 2026-08-05, in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.95-1 | Update the kernel and reboot. Fixed in 6.12.95-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.3-1 | Update the kernel and reboot. Fixed in 7.1.3-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.3-1 | Update the kernel and reboot. Fixed in 7.1.3-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Adapters can be looked up based on their id using i2c_get_adapter() which takes a reference to the embedded struct device. Make sure that the adapter (including its struct device) has been initialised before adding it to the IDR to avoid accessing uninitialised data which could, for example, lead to NULL-pointer dereferences or use-after-free. Note that the i2c-dev chardev, which is registered from a bus notifier, currently uses i2c_get_adapter() so the adapter needs to be added to the IDR before registration.
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/i2c/i2c-core-base.c
- What this is
- I2C SUBSYSTEMMAINTAINERS section matched on drivers/i2c/* · linux-i2c@vger.kernel.org · Maintained
- Kernel module
- i2c_core
Check it on the machine
grep -w CONFIG_I2C /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 i2c_corePrints 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.
- bookwormYnot built on amd64/cloud-amd64, arm64/cloud-arm64
- trixie, forky, sidBnot built on amd64/cloud-amd64, arm64/cloud-arm64
- Y
- built in where it is built at all; some flavours do not build it
- B
- built in on some, a module on others, absent on the rest
- Build switch
- CONFIG_I2C
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
- 2026-07-19 (3 months 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
- 0.11%, higher than 1.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/i2c
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.22 | 5.10.261 | 2e57c788e71f |
| 2.6.22 | 5.15.212 | a4365bc41baa |
| 2.6.22 | 6.1.178 | 1febb174815b |
| 2.6.22 | 6.6.145 | da9d8d9711f7 |
| 2.6.22 | 6.12.95 | 78793c75dc6d |
| 2.6.22 | 6.18.38 | 6a946038f2a5 |
| 2.6.22 | 7.1.3 | a4c8094bbf4c |
| 2.6.22 | 7.2 | ba14d7cf2fe7 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4723-1 | 2026-08-07 | bullseye 6.1.180-1~deb11u1 | tracker |
| DLA-4720-1 | 2026-08-05 | bookworm 6.1.180-1 | tracker |
| DLA-4717-1 | 2026-08-05 | bullseye 5.10.262-1 | 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 flaw is reached through local kernel I2C adapter registration/lookup paths (module load, hotplug, concurrent probe) and userspace access to /dev/i2c-* via open(); there is no remote network entry point to i2c_get_adapter().
- AC:LAttack complexity, low
- An attacker can repeatedly trigger adapter registration (e.g., modprobe/rmmod of I2C drivers, USB hotplug) while concurrently driving i2c_get_adapter() lookups, controlling both sides of the race window rather than depending on uncontrollable timing.
- PR:LPrivileges required, low
- Exploitation requires a local unprivileged user with basic capabilities such as membership in the i2c group for /dev/i2c-* access or CAP_SYS_MODULE within a user namespace to load I2C drivers, not full init-namespace root.
- UI:NUser interaction, none
- No victim interaction is required; the attacker can autonomously trigger the race through module loading, hotplug, and concurrent I2C device access.
- S:UScope, unchanged
- Impact is confined to kernel memory corruption and privilege escalation within the same security authority; this is not a VM escape or cross-boundary sandbox breakout.
- C:HConfidentiality impact, high
- Calling get_device() on an uninitialized struct device can cause use-after-free and read of uninitialized kobject memory, which the fix commit explicitly identifies as a UAF/info-disclosure class bug.
- I:HIntegrity impact, high
- Use-after-free and uninitialized kobject refcount corruption can be leveraged for arbitrary kernel memory writes and control-flow hijacking, consistent with UAF exploitation potential cited in the fix.
- A:HAvailability impact, high
- The race can trigger NULL-pointer dereferences or use-after-free in kernel context, causing oops/panic and complete loss of system availability.