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CVE-2026-74461
i2c: imx: Cancel hrtimer before clearing slave pointer
Published 2026-08-15 (2 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-2026-74461 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-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
In i2c_imx_unreg_slave(), the slave pointer is set to NULL after disabling interrupts. However, a pending interrupt might already have started the hrtimer (i2c_imx_slave_timeout) before the pointer was cleared. If the hrtimer fires after i2c_imx->slave is set to NULL, the timer callback i2c_imx_slave_finish_op() will call i2c_imx_slave_event() with a NULL slave pointer, which results in a use-after-free / NULL pointer dereference. Fix by canceling the hrtimer and waiting for it to complete after disabling interrupts, before clearing the slave pointer.
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/busses/i2c-imx.c
- What this is
- FREESCALE IMX I2C DRIVERMAINTAINERS section matched on drivers/i2c/busses/i2c-imx.c · linux-i2c@vger.kernel.org · Maintained
- Kernel module
- i2c_imx
Check it on the machine
grep -w CONFIG_I2C_IMX /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_imxPrints 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/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, i386/686, i386/686-pae, i386/rt/686-pae, ppc64el/powerpc64le
- trixieMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, armel/rpi, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, arm64/cloud-arm64, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_I2C_IMX
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
- 2026-08-15 (2 months 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 2.8% 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 |
|---|---|---|
| 5.11 | 5.15.216 | e3da77bdb401 |
| 5.11 | 6.1.183 | 470fe15fb3bb |
| 5.11 | 6.6.151 | a8a1f9ac3d76 |
| 5.11 | 6.12.103 | 753060f2b77f |
| 5.11 | 6.18.44 | affd62f5719a |
| 5.11 | 7.1.8 | dab4762ee7f3 |
| 5.11 | 7.2 | 6ac7702b6cc2 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | 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 in the imx I2C slave teardown path reached via i2c_slave_unregister during local driver removal on embedded i.MX systems; exploitation requires local proximity to trigger concurrent I2C bus activity on the same controller.
- AC:LAttack complexity, low
- The attacker controls both sides of the race by generating I2C slave traffic to arm/restart the 30us hrtimer while unregister runs, and can retry rapidly across repeated teardown cycles until the window is hit.
- PR:NPrivileges required, none
- No Linux credentials are required when an attacker with physical access to an exposed I2C bus races automated system maintenance (OTA, service restart, driver reload) that calls i2c_slave_unregister on imx slave backends.
- UI:NUser interaction, none
- Exploitation does not require victim interaction; automated firmware updates or service restarts that unregister the slave driver are sufficient to create the teardown side of the race.
- S:UScope, unchanged
- Impact is confined to kernel memory corruption and crash on the same host; this is not a VM escape, IOMMU bypass, or cross-security-authority boundary.
- C:HConfidentiality impact, high
- The timer callback invokes i2c_slave_event with a NULL/freed slave pointer (use-after-free), a memory safety violation that can be leveraged for arbitrary kernel memory read primitives per CVSS UAF guidance.
- I:HIntegrity impact, high
- Use-after-free in the slave event callback path can enable heap manipulation and arbitrary kernel write or control-flow hijack, not merely a deterministic NULL dereference crash.
- A:HAvailability impact, high
- Triggering i2c_slave_event with a NULL slave causes kernel oops/panic, and the original patch series notes the last_slave_event loop in i2c_imx_slave_finish_op can hang the system.