CVE-2026-72141 i2c: imx: fix locked bus on SMBus block-read of 0 (IRQ)
A flaw in the Linux kernel i2c-imx driver causes the I2C bus to lock up when handling zero-length SMBus block reads, requiring a power cycle to recover.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72141?
CVE-2026-72141 is a high-severity denial of service vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
i2c: imx: fix locked bus on SMBus block-read of 0 (IRQ)
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.
Which versions are affected by CVE-2026-72141?
How do I fix CVE-2026-72141?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-72141 being exploited?
There is no known exploitation of CVE-2026-72141 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72141, DEBIAN-CVE-2026-72141, GHSA-m5rq-h5xv-g5g9, UBUNTU-CVE-2026-72141.