CVE-2026-89736 - Vulnerability Details

- usb: gadget: u_audio: Fix use-after-free on sound card disconnect

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.

Published: 2026-09-11

Score: 7.8 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The u_audio USB gadget driver contains a use‑after‑free flaw (CWE‑825). When a sound card is disconnected while a userspace ALSA control element remains open, the driver before all ALSA references are released. Subsequent callbacks then dereference memorying kernel data and potentially allowing an attacker to execute arbitrary code with kernel privileges.

Affected Systems

All Linux kernel builds that include the u_audio gadget driver are affected. The vulnerability applies to both default kernel configurations and custom builds that enable the driver, whether it is compiled into the kernel or loaded as a module.

Risk and Exploitability

The vulnerability’s CVSS score of 7.8 indicates moderate to high severity. The EPSS of less than 1 % suggests a low current exploitation likelihood, and the flaw is not listed in CISA’s KEV catalog. Exploitation requires a local attacker to control the USB device, trigger a disconnect while a userspace control descriptor remains open, and then generate callbacks that access freed memory. If successful, the attacker could gain kernel‑level execution on the affected system.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`33f341c1fc60e172a3515c51bdabee11e83d1ee9`	affected	< a7ecd1a04f4f485d7be6443d0f0b2c61a800cb82
`b131989797f7287d7fdadb2bababc05a15d44750`	affected	< f983793f03148b097977f200298db215cd2d4438
`3bc7324e4911351e39c54a62e6ca46321cb10faf`	affected	< 6f46762196f04464e1050a9ee94e72b917db9010
`6c67ed9ad9b83e453e808f9b31a931a20a25629b`	affected	< 891a8d11f4d5eb50b2ce7570f4f98204a7a57493
`6c67ed9ad9b83e453e808f9b31a931a20a25629b`	affected	< c74ff0b1a0fca53d3ac185873c87d6a719b30a47
`6c67ed9ad9b83e453e808f9b31a931a20a25629b`	affected	< 4e747c864a88537e18b1ffc19a1954c9686bb8e1
`6c67ed9ad9b83e453e808f9b31a931a20a25629b`	affected	< 79a92896e2bb9471550c56fc23d8d93592f04c27
`6c67ed9ad9b83e453e808f9b31a931a20a25629b`	affected	< 858965947081d10d41d9a1010a540d3d5eea958b
`3e016ef2e72da93a2ea7afbb45de1b481b44d761`	affected	—
`3256e152b645fc1e788ba44c2d8ced690113e3e6`	affected	—
`0eda2004f38d95ef5715d62be884cd344260535b`	affected	—
`43ca70753dfffd517d2af126da28690f8f615605`	affected	—
`5.10.177`	affected	< 5.10.270
`5.15.105`	affected	< 5.15.221
`6.1.22`	affected	< 6.1.188
`4.14.312`	affected	< 4.15
`4.19.280`	affected	< 4.20
`5.4.240`	affected	< 5.5
`6.2.9`	affected	< 6.3

Linux

affected

Version	Status	Constraints
`6.3`	affected	—
`0`	unaffected	< 6.3
`5.10.270`	unaffected	≤ 5.10.*
`5.15.221`	unaffected	≤ 5.15.*
`6.1.188`	unaffected	≤ 6.1.*
`6.6.157`	unaffected	≤ 6.6.*
`6.12.109`	unaffected	≤ 6.12.*
`6.18.50`	unaffected	≤ 6.18.*
`7.2.4`	unaffected	≤ 7.2.*
`7.3-rc1`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[6c67ed9ad9b83e453e808f9b31a931a20a25629b,c74ff0b1a0fca53d3ac185873c87d6a719b30a47)`	affected	generic	—
`[6c67ed9ad9b83e453e808f9b31a931a20a25629b,4e747c864a88537e18b1ffc19a1954c9686bb8e1)`	affected	generic	—
`[6c67ed9ad9b83e453e808f9b31a931a20a25629b,79a92896e2bb9471550c56fc23d8d93592f04c27)`	affected	generic	—
`[6c67ed9ad9b83e453e808f9b31a931a20a25629b,858965947081d10d41d9a1010a540d3d5eea958b)`	affected	generic	—
`3e016ef2e72da93a2ea7afbb45de1b481b44d761`	affected	generic	—
`3256e152b645fc1e788ba44c2d8ced690113e3e6`	affected	generic	—
`0eda2004f38d95ef5715d62be884cd344260535b`	affected	generic	—
`33f341c1fc60e172a3515c51bdabee11e83d1ee9`	affected	generic	—
`b131989797f7287d7fdadb2bababc05a15d44750`	affected	generic	—
`3bc7324e4911351e39c54a62e6ca46321cb10faf`	affected	generic	—
`43ca70753dfffd517d2af126da28690f8f615605`	affected	generic	—
`[4.14.312,4.15)`	affected	semver	—
`[4.19.280,4.20)`	affected	semver	—
`[5.4.240,5.5)`	affected	semver	—
`[5.10.177,5.11)`	affected	semver	—
`[5.15.105,5.16)`	affected	semver	—
`[6.1.22,6.2)`	affected	semver	—
`[6.2.9,6.3)`	affected	semver	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`6.3`	affected	generic	—
`[0,6.3)`	unaffected	generic	—
`[6.12.109,6.13.0)`	unaffected	semver	—
`[6.18.50,6.19.0)`	unaffected	semver	—
`[7.2.4,7.3.0)`	unaffected	semver	—
`[7.3-rc1,*]`	unaffected	generic	—

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Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Update the kernel to a version that includes the u_audio use‑after‑free fix.
Reboot the system to load the updated kernel and unload any residual old u_audio driver modules.
If an immediate kernel update cannot be performed, disable or remove the USB audio gadget device or unload the u_audio module until the patch can be applied.

Generated by OpenCVE AI on September 15, 2026 at 19:20 UTC.

Tracking

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Advisories

Source	ID	Title
Debian DSA	DSA-6528-1	linux security update

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00171.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/4e747c864a88537e18b1ffc19a1954c9686bb8e1
https://git.kernel.org/stable/c/6f46762196f04464e1050a9ee94e72b917db9010
https://git.kernel.org/stable/c/79a92896e2bb9471550c56fc23d8d93592f04c27
https://git.kernel.org/stable/c/858965947081d10d41d9a1010a540d3d5eea958b
https://git.kernel.org/stable/c/891a8d11f4d5eb50b2ce7570f4f98204a7a57493
https://git.kernel.org/stable/c/a7ecd1a04f4f485d7be6443d0f0b2c61a800cb82
https://git.kernel.org/stable/c/c74ff0b1a0fca53d3ac185873c87d6a719b30a47
https://git.kernel.org/stable/c/f983793f03148b097977f200298db215cd2d4438
https://nvd.nist.gov/vuln/detail/CVE-2026-89736
https://www.cve.org/CVERecord?id=CVE-2026-89736

History

Mon, 14 Sep 2026 12:30:00 +0000

Type	Values Removed	Values Added
References		https://git.kernel.org/stable/c/6f46762196f04464e1050a9ee94e72b917db9010 https://git.kernel.org/stable/c/891a8d11f4d5eb50b2ce7570f4f98204a7a57493 https://git.kernel.org/stable/c/a7ecd1a04f4f485d7be6443d0f0b2c61a800cb82 https://git.kernel.org/stable/c/f983793f03148b097977f200298db215cd2d4438

Sun, 13 Sep 2026 06:45:00 +0000

Type	Values Removed	Values Added
Metrics	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}`	cvssV3_1 `{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}`

Sat, 12 Sep 2026 00:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-825
References		https://nvd.nist.gov/vuln/detail/CVE-2026-89736 https://www.cve.org/CVERecord?id=CVE-2026-89736
Metrics	threat_severity `None`	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}` threat_severity `Important`

Fri, 11 Sep 2026 23:45:00 +0000

Type	Values Removed	Values Added
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.
Title		usb: gadget: u_audio: Fix use-after-free on sound card disconnect
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/4e747c864a88537e18b1ffc19a1954c9686bb8e1 https://git.kernel.org/stable/c/79a92896e2bb9471550c56fc23d8d93592f04c27 https://git.kernel.org/stable/c/858965947081d10d41d9a1010a540d3d5eea958b https://git.kernel.org/stable/c/c74ff0b1a0fca53d3ac185873c87d6a719b30a47

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-09-11T19:46:44.608Z

Updated: 2026-09-14T12:02:23.539Z

Reserved: 2026-09-11T19:38:34.761Z

Link: CVE-2026-89736

Vulnrichment

No data.

NVD

Status : Received

Published: 2026-09-11T20:20:04.077

Modified: 2026-09-14T13:19:22.700

Link: CVE-2026-89736

Redhat

Severity : Important

Publid Date: 2026-09-11T19:46:44Z

Links: CVE-2026-89736 - Bugzilla

OpenCVE Enrichment

Updated: 2026-09-15T19:30:12Z

Weaknesses

CWE-825
Expired Pointer Dereference

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Subscriptions

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