CVE-2026-80886 serial: msm: Disable DMA for kernel console UART
A race condition in the Linux kernel MSM serial driver can cause an infinite loop during concurrent writes, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80886?
CVE-2026-80886 is a vulnerability in Linux, published on 4 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:
serial: msm: Disable DMA for kernel console UART
At the moment, concurrent writes from userspace and the kernel to the console can trigger a race condition that results in an infinite loop of the same messages printed over and over again. This is most likely to happen during system startup or shutdown when the init system starts/stops a large number of system services that interact with various kernel code.
When userspace writes to the TTY device, the driver initiates an asynchronous DMA transfer and releases the port lock. At the same moment, the kernel printk path might grab the port lock and re-configure the UART controller for PIO, without waiting for the DMA operation to complete. It seems like this collision results in zero progress being reported for the DMA engine, so the same text is printed to the console over and over again.
For the kernel console, we want a reliable output path that will be functional even during crashes etc. So rather than implementing complex code to synchronize the kernel console write routines with the userspace DMA write routines, simply disable DMA for the console UART instance.
Similar checks exist in many other serial drivers, e.g. 8250_port.c, imx.c, sh-sci.c etc.
Which versions are affected by CVE-2026-80886?
How do I fix CVE-2026-80886?
Apply the vendor's patch.
Is CVE-2026-80886 being exploited?
There is no known exploitation of CVE-2026-80886 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80886, DEBIAN-CVE-2026-80886, GHSA-f3wr-g9f6-6vgf, UBUNTU-CVE-2026-80886.