CVE-2026-43340 comedi: Reinit dev->spinlock between attachments to low-level drivers
A race condition in the Linux kernel COMEDI subsystem can cause lock state inconsistencies and potential denial of service when devices are reattached.
- 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-2026-43340?
CVE-2026-43340 is a medium-severity vulnerability in Linux kernel, published on 8 May 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:
comedi: Reinit dev->spinlock between attachments to low-level drivers
`struct comedi_device` is the main controlling structure for a COMEDI device created by the COMEDI subsystem. It contains a member `spinlock` containing a spin-lock that is initialized by the COMEDI subsystem, but is reserved for use by a low-level driver attached to the COMEDI device (at least since commit 25436dc9d84f ("Staging: comedi: remove RT code")).
Some COMEDI devices (those created on initialization of the COMEDI subsystem when the "comedi.comedi_num_legacy_minors" parameter is non-zero) can be attached to different low-level drivers over their lifetime using the `COMEDI_DEVCONFIG` ioctl command. This can result in inconsistent lock states being reported when there is a mismatch in the spin-lock locking levels used by each low-level driver to which the COMEDI device has been attached. Fix it by reinitializing `dev->spinlock` before calling the low-level driver's `attach` function pointer if `CONFIG_LOCKDEP` is enabled.
Which versions are affected by CVE-2026-43340?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43340?
Apply the vendor's patch.
Is CVE-2026-43340 being exploited?
There is no known exploitation of CVE-2026-43340 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43340, DEBIAN-CVE-2026-43340, GHSA-cxcr-vph9-wv8j, ROOT-OS-DEBIAN-11-CVE-2026-43340, ROOT-OS-UBUNTU-2204-CVE-2026-43340, ROOT-OS-UBUNTU-2404-CVE-2026-43340 and 1 more.