CVE-2026-93123 serial: qcom-geni: do not advance stale DMA completions
A race condition in the Qualcomm GENI serial driver allows stale DMA completions to discard new transmit data, causing data loss and potential 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-2026-93123?
CVE-2026-93123 is a vulnerability in Linux, published on 17 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: qcom-geni: do not advance stale DMA completions
The qcom GENI serial DMA TX completion path advances the transmit fifo by the number of bytes recorded in port->tx_remaining.
If uart_flush_buffer() runs after the hardware has completed a DMA transfer but before the DMA completion interrupt has been handled, the serial core resets the transmit fifo while port->tx_remaining still describes the old DMA transfer.
A previous fix avoided advancing an empty fifo by checking that the fifo length is at least tx_remaining. That still does not distinguish the old DMA payload from new bytes written after the flush. If userspace writes new data before the stale DMA completion interrupt is handled, the fifo can again contain at least tx_remaining bytes and the stale completion can advance and discard those new bytes.
Mark an in-flight DMA transfer stale when the transmit fifo is flushed. The later completion still unprepares the original DMA mapping using the saved length, but it no longer advances the transmit fifo.
Which versions are affected by CVE-2026-93123?
How do I fix CVE-2026-93123?
Apply the vendor's patch.
Is CVE-2026-93123 being exploited?
There is no known exploitation of CVE-2026-93123 in the wild and no public exploit code.
Sources
Also known as AZL-102575, BELL-CVE-2026-93123, DEBIAN-CVE-2026-93123, GHSA-68q2-cr9g-x9r8, UBUNTU-CVE-2026-93123.