CVE-2026-89736: Linux Vulnerability (CVSS 7.8)

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.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.13%

2.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 33f341c1fc60e172a3515c51bdabee11e83d1ee9, < a7ecd1a04f4f485d7be6443d0f0b2c61a800cb82; >= b131989797f7287d7fdadb2bababc05a15d44750, < f983793f03148b097977f200298db215cd2d4438; >= 3bc7324e4911351e39c54a62e6ca46321cb10faf, < 6f46762196f04464e1050a9ee94e72b917db9010; >= 6c67ed9ad9b83e453e808f9b31a931a20a25629b, < 891a8d11f4d5eb50b2ce7570f4f98204a7a57493; >= 6c67ed9ad9b83e453e808f9b31a931a20a25629b, < c74ff0b1a0fca53d3ac185873c87d6a719b30a47; >= 6c67ed9ad9b83e453e808f9b31a931a20a25629b, < 4e747c864a88537e18b1ffc19a1954c9686bb8e1; >= 6c67ed9ad9b83e453e808f9b31a931a20a25629b, < 79a92896e2bb9471550c56fc23d8d93592f04c27; >= 6c67ed9ad9b83e453e808f9b31a931a20a25629b, < 858965947081d10d41d9a1010a540d3d5eea958b; 3e016ef2e72da93a2ea7afbb45de1b481b44d761; 3256e152b645fc1e788ba44c2d8ced690113e3e6; 0eda2004f38d95ef5715d62be884cd344260535b; 43ca70753dfffd517d2af126da28690f8f615605; >= 5.10.177, < 5.10.270; >= 5.15.105, < 5.15.221; >= 6.1.22, < 6.1.188; >= 4.14.312, < 4.15; >= 4.19.280, < 4.20; >= 5.4.240, < 5.5; >= 6.2.9, < 6.3
Linux	Linux	6.3

References

Timeline

Published: Sep 11, 2026
Last Modified: Sep 14, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-89736?

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.

How severe is CVE-2026-89736?

CVE-2026-89736 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.13% probability of exploitation in the next 30 days.

How do I fix CVE-2026-89736?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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