# CVE-2026-31723: usb: gadget: f_subset: Fix net_device lifecycle with device_move

CVE-2026-31723 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-31723, released May 15, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-31723
- Priority: High
- CVSS: 7.8 (Important)
- EPSS: 0.0016
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 1, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-31723

## Description

In the Linux kernel, the following vulnerability has been resolved:  usb: gadget: f_subset: Fix net_device lifecycle with device_move  The net_device is allocated during function instance creation and registered during the bind phase with the gadget device as its sysfs parent. When the function unbinds, the parent device is destroyed, but the net_device survives, resulting in dangling sysfs symlinks:    console:/ # ls -l /sys/class/net/usb0   lrwxrwxrwx ... /sys/class/net/usb0 ->   /sys/devices/platform/.../gadget.0/net/usb0   console:/ # ls -l /sys/devices/platform/.../gadget.0/net/usb0   ls: .../gadget.0/net/usb0: No such file or directory  Use device_move() to reparent the net_device between the gadget device tree and /sys/devices/virtual across bind and unbind cycles. During the final unbind, calling device_move(NULL) moves the net_device to the virtual device tree before the gadget device is destroyed. On rebinding, device_move() reparents the device back under the new gadget, ensuring proper sysfs topology and power management ordering.  To maintain compatibility with legacy composite drivers (e.g., multi.c), the bound flag is used to indicate whether the network device is shared and pre-registered during the legacy driver's bind phase.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.85-1 | [DEBIAN-CVE-2026-31723](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31723.md) | May 15, 2026 |
| Linux | linux Debian 14 | 6.19.12-1 | [DEBIAN-CVE-2026-31723](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31723.md) | May 15, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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