CVE-2026-89940 iio: buffer: Tie IIO dma fence lock lifetime to the fence
A use-after-free vulnerability in the Linux kernel IIO DMA fence implementation allows attackers to potentially execute code or escalate privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89940?
CVE-2026-89940 is a high-severity use after free vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
iio: buffer: Tie IIO dma fence lock lifetime to the fence
The `iio_dma_fence` implementation currently uses a lock embedded in the `iio_dmabuf_priv`. But the `iio_dma_fence` can outlive the `iio_dmabuf_priv`, which can cause a use-after-free.
Tie the lifetime of the lock to the lifetime of the fence by embedding them in the same struct.
We can't just hold a reference to the `iio_dmabuf_priv` from the `iio_dma_fence` since `iio_buffer_dmabuf_release()` might sleep and the fence release callback is not allowed to sleep.
Note that the `dma_fence` framework now has an internal lock that gets used when the passing `NULL` for `lock` in `dma_fence_init()`, but in order to allow this patch to be backportable use an external lock.
Which versions are affected by CVE-2026-89940?
How do I fix CVE-2026-89940?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-89940 being exploited?
There is no known exploitation of CVE-2026-89940 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-89940, DEBIAN-CVE-2026-89940, GHSA-rvmw-48g6-x73g, UBUNTU-CVE-2026-89940.