# 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.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102575, BELL-CVE-2026-93123, DEBIAN-CVE-2026-93123, GHSA-68q2-cr9g-x9r8, UBUNTU-CVE-2026-93123

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93123 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-93123 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-93123/ (Markdown: https://insights.sbomify.com/CVE-2026-93123/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93123
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93123
- OSV: https://osv.dev/vulnerability/CVE-2026-93123

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93123/
Summaries are generated and may contain mistakes; the official description above is the record.