In the Linux kernel, the following vulnerability has been resolved:
media: usbtv: keep device alive while ALSA card exists
The ALSA PCM callbacks store the driver state in pcm->private_data. An
open PCM file can outlive USB disconnect because usbtv_audio_free() uses
snd_card_free_when_closed(). The disconnect path can then drop the V4L2
device reference and free struct usbtv before ALSA releases the substream,
so a later close dereferences freed memory in snd_usbtv_pcm_close().
Take a V4L2 device reference for the ALSA card and drop it from the card
private_free callback. This keeps struct usbtv valid until ALSA has closed
the remaining files and freed the card.
CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 7.8
AV:L - The UAF is reached locally by opening the usbtv ALSA capture PCM, forcing usbtv_disconnect() via USBDEVFS_DISCONNECT or sysfs unbind on an already-bound USBTV007, then closing the PCM fd; there is no network or packet path. This matches AV:L scoring of analogous USB disconnect UAFs (CVE-2026-80971, CVE-2026-64585); physical unplug is only an extra path.
AC:L - The attacker fully controls the sequence: open /dev/snd/pcmCDc so PCM callbacks pin pcm->private_data, issue USBDEVFS_DISCONNECT so snd_card_free_when_closed() returns without waiting, then close. That close deterministically hits freed struct usbtv in snd_usbtv_pcm_close(); no attacker-uncontrollable race or layout is required.
PR:L - USBDEVFS_DISCONNECT has no capable() check, only write access to /dev/bus/usb that udev uaccess/plugdev rules grant seat users, and snd_pcm_open() has no capability gate on the capture PCM node (audio group/uaccess). An unprivileged local account suffices; init-namespace root is not required.
UI:N - The attacker performs open, disconnect, and close on their own fds against an already-attached USBTV007 (capture kiosk, digitizer, or surveillance station). No separate victim action such as plugging a device or clicking is required during exploitation.
S:U - The slab use-after-free of struct usbtv and the PCM close/trigger callbacks run entirely in the host kernel. This is ordinary local privilege escalation, not a VM, IOMMU, or sandbox boundary escape.
C:H - snd_usbtv_pcm_close() and snd_usbtv_card_trigger() read fields of the kfree()'d struct usbtv (snd_stream, snd_trigger, snd_bulk_urb). Reclaiming that slab lets the attacker supply pointer-rich state those paths then read, enabling kernel disclosure as with other heap UAFs.
I:H - Close can atomic_set snd_stream and schedule_work() on the freed usbtv.snd_trigger work_struct, and snd_pcm_drop may call trigger STOP on the same freed object. A reclaimed fake usbtv plus workqueue execution is a control-flow hijack primitive, so integrity impact is High.
A:H - Use-after-free of struct usbtv in snd_usbtv_pcm_close() (and in usbtv_audio_urb_received if capture was running when USB core kills the URB after disconnect) oopses or panics the kernel. The attacker can repeat disconnect/close to crash on demand, so availability impact is High.
| Attack Vector |
Local |
Scope |
Unchanged |
| Attack Complexity |
Low |
Confidentiality Impact |
High |
| Privileges Required |
Low |
Integrity Impact |
High |
| User Interaction |
None |
Availability Impact |
High |
AV:L - The UAF is reached locally by opening the usbtv ALSA capture PCM, forcing usbtv_disconnect() via USBDEVFS_DISCONNECT or sysfs unbind on an already-bound USBTV007, then closing the PCM fd; there is no network or packet path. This matches AV:L scoring of analogous USB disconnect UAFs (CVE-2026-80971, CVE-2026-64585); physical unplug is only an extra path.
AC:L - The attacker fully controls the sequence: open /dev/snd/pcmCDc so PCM callbacks pin pcm->private_data, issue USBDEVFS_DISCONNECT so snd_card_free_when_closed() returns without waiting, then close. That close deterministically hits freed struct usbtv in snd_usbtv_pcm_close(); no attacker-uncontrollable race or layout is required.
PR:L - USBDEVFS_DISCONNECT has no capable() check, only write access to /dev/bus/usb that udev uaccess/plugdev rules grant seat users, and snd_pcm_open() has no capability gate on the capture PCM node (audio group/uaccess). An unprivileged local account suffices; init-namespace root is not required.
UI:N - The attacker performs open, disconnect, and close on their own fds against an already-attached USBTV007 (capture kiosk, digitizer, or surveillance station). No separate victim action such as plugging a device or clicking is required during exploitation.
S:U - The slab use-after-free of struct usbtv and the PCM close/trigger callbacks run entirely in the host kernel. This is ordinary local privilege escalation, not a VM, IOMMU, or sandbox boundary escape.
C:H - snd_usbtv_pcm_close() and snd_usbtv_card_trigger() read fields of the kfree()'d struct usbtv (snd_stream, snd_trigger, snd_bulk_urb). Reclaiming that slab lets the attacker supply pointer-rich state those paths then read, enabling kernel disclosure as with other heap UAFs.
I:H - Close can atomic_set snd_stream and schedule_work() on the freed usbtv.snd_trigger work_struct, and snd_pcm_drop may call trigger STOP on the same freed object. A reclaimed fake usbtv plus workqueue execution is a control-flow hijack primitive, so integrity impact is High.
A:H - Use-after-free of struct usbtv in snd_usbtv_pcm_close() (and in usbtv_audio_urb_received if capture was running when USB core kills the URB after disconnect) oopses or panics the kernel. The attacker can repeat disconnect/close to crash on demand, so availability impact is High.
CVSS 3.1