CVE-2026-74654 serial: 8250_dma: Clear stale RX state on shutdown
A null pointer dereference in the Linux kernel serial driver causes a kernel Oops when reopening a port with stale DMA state, leading to 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-2026-74654?
CVE-2026-74654 is a vulnerability in Linux, published on 22 Aug 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: 8250_dma: Clear stale RX state on shutdown
serial8250_release_dma() terminates RX DMA and releases the channel, but leaves rx_running set. If the port is closed while an RX transfer is active, the stale state remains while rxchan is NULL until the channel is requested again on the next open.
The DesignWare BUSY workaround added by commit a7b9ce39fbe4 ("serial: 8250_dw: Ensure BUSY is deasserted") calls serial8250_rx_dma_flush() from the LCR write path during startup. This happens before serial8250_request_dma() obtains a new RX channel. On reopen, the stale rx_running state therefore makes the flush path pass a NULL channel to dmaengine_pause(), causing a kernel Oops.
Clear rx_running after terminating RX DMA, matching the TX cleanup. Also make the flush helper return if the DMA object or RX channel is not available so startup and teardown paths cannot pass a NULL channel to the DMAengine API.
Which versions are affected by CVE-2026-74654?
How do I fix CVE-2026-74654?
Apply the vendor's patch.
Is CVE-2026-74654 being exploited?
There is no known exploitation of CVE-2026-74654 in the wild and no public exploit code.
Sources
Also known as AZL-97346, BELL-CVE-2026-74654, DEBIAN-CVE-2026-74654, GHSA-m9j6-hfqp-5v8v, UBUNTU-CVE-2026-74654.