Look up another CVE · open CVE-2026-72141 in the interactive tracker
CVE-2026-72141
i2c: imx: fix locked bus on SMBus block-read of 0 (IRQ)
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/i2c. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-72141 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 | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
SMBus 3.1 6.5.7 allows a Block Read byte count of 0, but the interrupt-driven block-read state machine rejects it as -EPROTO. Worse, it returns without a NACK+STOP: the next receive cycle has already started, so the target keeps holding SDA and the bus stays stuck until a power cycle of this i2c controller. Accept count=0: NACK the in-flight dummy byte (TXAK) and set msg->len to 2 so i2c_imx_isr_read_continue() emits STOP via its normal last-byte path. The dummy byte is discarded; block-read callers only consume buf[0..count-1]. Reading I2DR has likewise already armed the next byte on the count > I2C_SMBUS_BLOCK_MAX error path, so NACK it (TXAK) before aborting with -EPROTO; otherwise the failing transfer's STOP cannot complete and the bus stays held. The atomic path regressed earlier (v3.16) and is fixed separately; this patch covers only the v6.13 state-machine rework.
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
- 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
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.61%, higher than 48.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- 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 |
|---|---|---|
| 6.13 | 6.18.40 | 5d3240f42a66 |
| 6.13 | 7.1.5 | 56ddfc18ea8f |
| 6.13 | 7.2 | 07fd9385f0d8 |
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:NAttack vector, network
- On NXP Layerscape/i.MX appliances, remotely reachable IPMI-over-LAN or management-plane requests invoke ipmi_ssif/pmbus i2c_smbus_read_block_data() on imx-i2c; a malicious or compromised bus peripheral returning SMBus block-read count 0 reaches the vulnerable IRQ handler without local login.
- AC:LAttack complexity, low
- Once an SMBus block-read transaction is initiated and the target returns count byte 0 (a valid SMBus 3.1 response), the IRQ path deterministically omits NACK/STOP and locks the bus; the attacker controls both transaction initiation and slave response via compromised BMC/PMBus device or planted peripheral.
- PR:NPrivileges required, none
- No Linux credentials are required when a malicious or compromised I2C slave returns count 0 during kernel-initiated SMBus block reads from IPMI SSIF, PMBus hwmon polling, or other automated drivers; OS privilege is not needed beyond influencing the bus response.
- UI:NUser interaction, none
- Exploitation requires no victim interaction because kernel subsystems (IPMI SSIF, PMBus hwmon, sensor drivers) automatically perform SMBus block reads during normal remote-management or background monitoring operations once the bus device responds.
- S:UScope, unchanged
- Impact is confined to locking the imx-i2c controller and attached I2C bus within the same kernel/host security boundary; it does not cross VM, container, or IOMMU isolation boundaries.
- C:NConfidentiality impact, none
- The flaw is a missing NACK/STOP during SMBus block-read length handling; it causes a stuck I2C bus but does not corrupt kernel memory, leak data, or provide read primitives.
- I:NIntegrity impact, none
- No kernel or user data is modified; the bug only leaves the I2C controller in a hung bus state without write primitives, code execution, or integrity violations beyond loss of bus function.
- A:HAvailability impact, high
- A successful trigger permanently locks the imx-i2c bus until controller power-cycle, denying all further I2C/SMBus communication to PMICs, sensors, EEPROMs, and BMC SSIF on safety-critical embedded, automotive, and datacenter systems.