CVE-2026-89736: Linux

High severity, CVSS 7.8. EPSS: 0.1% chance of exploitation in the next 30 days.

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.

Affected products

• Linux Linux: from 5.10.177, before 5.10.270 (fixed in 5.10.270); from 5.15.105, before 5.15.221 (fixed in 5.15.221); from 6.1.22, before 6.1.188 (fixed in 6.1.188); from 4.14.312, before 4.15 (fixed in 4.15); from 4.19.280, before 4.20 (fixed in 4.20); from 5.4.240, before 5.5 (fixed in 5.5); …

Published 2026-09-11. Last modified 2026-09-14.