In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_rndis: Fix net_device lifecycle with device_move The net_device… (CVE-2026-31722)
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_rndis: 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 borrowed_net flag is used to indicate whether the network device is shared and pre-registered during the legacy driver's bind phase.
AI Analysis
Technical Summary
The Linux kernel vulnerability (CVE-2026-31722) concerns the usb gadget subsystem's f_rndis function, where the net_device object is allocated during function instance creation and registered with the gadget device as its sysfs parent. Upon unbinding, the parent device is destroyed but the net_device remains, resulting in dangling sysfs symlinks. This improper lifecycle management was addressed by using device_move() to reparent the net_device between the gadget device tree and the virtual device tree during bind and unbind cycles, ensuring no dangling references remain. The vulnerability affects multiple Ubuntu Linux kernel versions prior to 6.8.0-1061.64~22.04.1 and related versions. The issue was fixed in official Ubuntu kernel updates as part of a broader security update addressing numerous kernel vulnerabilities. The CVSS 3.1 vector is AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating local attack vector with low complexity, requiring low privileges, no user interaction, unchanged scope, no confidentiality or integrity impact, but high impact on availability.
Potential Impact
The vulnerability can cause dangling sysfs symlinks due to net_device objects surviving after their parent gadget device is destroyed, potentially leading to system instability or denial of service (availability impact). There is no confidentiality or integrity impact reported. The CVSS score of 5.5 reflects a medium severity primarily due to availability impact. No known exploits in the wild have been reported.
Mitigation Recommendations
A patch fixing this vulnerability is available and has been incorporated into updated Linux kernel packages for affected Ubuntu releases. Users should apply the official kernel updates and reboot their systems to ensure the fix is applied. Due to an ABI change in the kernel update, recompilation and reinstallation of any third-party kernel modules may be required. Follow vendor instructions for updating and rebuilding kernel modules as necessary.
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_rndis: Fix net_device lifecycle with device_move The net_device… (CVE-2026-31722)
Description
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_rndis: 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 borrowed_net flag is used to indicate whether the network device is shared and pre-registered during the legacy driver's bind phase.
CVSS v3.1
Score 5.5medium
Affected software
pkg:deb/ubuntu/[email protected]?arch=source&distro=esm-infra-legacy/trustypkg:deb/ubuntu/[email protected]?arch=source&distro=esm-infra-legacy/trustypkg:deb/ubuntu/[email protected]~14.04.1?arch=source&distro=esm-infra-legacy/trustypkg:deb/ubuntu/[email protected]~14.04.1?arch=source&distro=esm-infra-legacy/trustypkg:deb/ubuntu/[email protected]?arch=source&distro=esm-infra-legacy/xenialpkg:deb/ubuntu/[email protected]?arch=source&distro=esm-infra-legacy/xenialpkg:deb/ubuntu/[email protected]~16.04.1?arch=source&distro=esm-infra-legacy/xenialpkg:deb/ubuntu/[email protected]~16.04.1?arch=source&distro=esm-infra-legacy/xenialpkg:deb/ubuntu/[email protected]~16.04.1?arch=source&distro=esm-infra-legacy/xenialpkg:deb/ubuntu/[email protected]~16.04.1?arch=source&distro=esm-infra-legacy/xenialpkg:deb/ubuntu/[email protected]~16.04.1?arch=source&distro=xenialpkg:deb/ubuntu/[email protected]?arch=source&distro=esm-infra-legacy/xenialpkg:deb/ubuntu/[email 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protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resoluteRun on your own infrastructure? 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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel vulnerability (CVE-2026-31722) concerns the usb gadget subsystem's f_rndis function, where the net_device object is allocated during function instance creation and registered with the gadget device as its sysfs parent. Upon unbinding, the parent device is destroyed but the net_device remains, resulting in dangling sysfs symlinks. This improper lifecycle management was addressed by using device_move() to reparent the net_device between the gadget device tree and the virtual device tree during bind and unbind cycles, ensuring no dangling references remain. The vulnerability affects multiple Ubuntu Linux kernel versions prior to 6.8.0-1061.64~22.04.1 and related versions. The issue was fixed in official Ubuntu kernel updates as part of a broader security update addressing numerous kernel vulnerabilities. The CVSS 3.1 vector is AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating local attack vector with low complexity, requiring low privileges, no user interaction, unchanged scope, no confidentiality or integrity impact, but high impact on availability.
Potential Impact
The vulnerability can cause dangling sysfs symlinks due to net_device objects surviving after their parent gadget device is destroyed, potentially leading to system instability or denial of service (availability impact). There is no confidentiality or integrity impact reported. The CVSS score of 5.5 reflects a medium severity primarily due to availability impact. No known exploits in the wild have been reported.
Mitigation Recommendations
A patch fixing this vulnerability is available and has been incorporated into updated Linux kernel packages for affected Ubuntu releases. Users should apply the official kernel updates and reboot their systems to ensure the fix is applied. Due to an ABI change in the kernel update, recompilation and reinstallation of any third-party kernel modules may be required. Follow vendor instructions for updating and rebuilding kernel modules as necessary.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-31722
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:Pro:14.04:LTS","Ubuntu:Pro:16.04:LTS","Ubuntu:16.04:LTS","Ubuntu:Pro:FIPS:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:18.04:LTS","Ubuntu:Pro:FIPS-updates:18.04:LTS","Ubuntu:Pro:FIPS:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:20.04:LTS","Ubuntu:Pro:FIPS-updates:20.04:LTS","Ubuntu:Pro:FIPS:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:Nvidia-BlueField:22.04:LTS","Ubuntu:Pro:FIPS-preview:22.04:LTS","Ubuntu:Pro:FIPS-updates:22.04:LTS","Ubuntu:Pro:Realtime:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:Nvidia-BlueField:24.04:LTS","Ubuntu:Pro:FIPS-updates:24.04:LTS","Ubuntu:Pro:Realtime:24.04:LTS","Ubuntu:25.10","Ubuntu:26.04:LTS"]
- Cvss Version
- 3.1
Threat ID: 6a5b61aa2d1edb114c884867
Added to database: 07/18/2026, 11:21:14 UTC
Last enriched: 08/01/2026, 04:51:27 UTC
Last updated: 09/14/2026, 22:01:33 UTC
Views: 26
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