Description
In the Linux kernel, the following vulnerability has been resolved:
usb: usbfs: fix use-after-free of usb_device in usbdev_release()
usbdev_release() drops its reference to the struct usb_device before
draining the list of completed async URBs, but that drain path reads back
through the same object: free_async() calls dec_usb_memory_use_count()
for any URB whose buffer came from the usbfs mmap() region, and its first
statement is bus_to_hcd(ps->dev->bus).
After a disconnect the usbfs reference can be the last one, in which case
usb_put_dev() frees the device and the subsequent loop reads offset 80 of
freed memory and uses the result as a struct usb_hcd *, which
hcd_buffer_free_pages() then dereferences.
This is reachable by an unprivileged process that has read/write access to
a /dev/bus/usb node: mmap() the fd, submit one URB with a buffer inside the
mapping, wait for the device to be unplugged, then munmap() and close().
It reproduces on every attempt rather than being a race, because a live
MAP_SHARED vma holds a reference on the struct file, so usbdev_release()
cannot run until the last vma is gone and the freeing branch of
dec_usb_memory_use_count() is always taken.
BUG: KASAN: slab-use-after-free in dec_usb_memory_use_count+0x3ae/0x410
Read of size 8 at addr ffff8880122ee050 by task poc/769
CPU: 1 UID: 1000 PID: 769 Comm: poc Tainted: G B 6.12.94 #3
Call Trace:
dec_usb_memory_use_count+0x3ae/0x410
free_async+0x2aa/0x4f0
usbdev_release+0x375/0x460
__fput+0x3ea/0xb50
__x64_sys_close+0x86/0x100
Allocated by task 11:
usb_alloc_dev+0x55/0xd90
hub_event+0x2524/0x43d0
Freed by task 769:
kfree+0x121/0x360
device_release+0xd2/0x280
usb_put_dev+0x23/0x30
usbdev_release+0x2d8/0x460
Release the device reference after the drain loop instead. Nothing between
the two points requires it to have been dropped.
usb: usbfs: fix use-after-free of usb_device in usbdev_release()
usbdev_release() drops its reference to the struct usb_device before
draining the list of completed async URBs, but that drain path reads back
through the same object: free_async() calls dec_usb_memory_use_count()
for any URB whose buffer came from the usbfs mmap() region, and its first
statement is bus_to_hcd(ps->dev->bus).
After a disconnect the usbfs reference can be the last one, in which case
usb_put_dev() frees the device and the subsequent loop reads offset 80 of
freed memory and uses the result as a struct usb_hcd *, which
hcd_buffer_free_pages() then dereferences.
This is reachable by an unprivileged process that has read/write access to
a /dev/bus/usb node: mmap() the fd, submit one URB with a buffer inside the
mapping, wait for the device to be unplugged, then munmap() and close().
It reproduces on every attempt rather than being a race, because a live
MAP_SHARED vma holds a reference on the struct file, so usbdev_release()
cannot run until the last vma is gone and the freeing branch of
dec_usb_memory_use_count() is always taken.
BUG: KASAN: slab-use-after-free in dec_usb_memory_use_count+0x3ae/0x410
Read of size 8 at addr ffff8880122ee050 by task poc/769
CPU: 1 UID: 1000 PID: 769 Comm: poc Tainted: G B 6.12.94 #3
Call Trace:
dec_usb_memory_use_count+0x3ae/0x410
free_async+0x2aa/0x4f0
usbdev_release+0x375/0x460
__fput+0x3ea/0xb50
__x64_sys_close+0x86/0x100
Allocated by task 11:
usb_alloc_dev+0x55/0xd90
hub_event+0x2524/0x43d0
Freed by task 769:
kfree+0x121/0x360
device_release+0xd2/0x280
usb_put_dev+0x23/0x30
usbdev_release+0x2d8/0x460
Release the device reference after the drain loop instead. Nothing between
the two points requires it to have been dropped.
Published:
2026-09-04
Score:
n/a
EPSS:
n/a
KEV:
No
Impact:
n/a
Action:
n/a
Analysis
No analysis available yet.
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 | Linux | unaffected |
|
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| Linux | Linux | affected |
|
No data.
No data.
No data available yet.
Remediation
No remediation available yet.
Tracking
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Advisories
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References
History
Fri, 04 Sep 2026 16:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: usb: usbfs: fix use-after-free of usb_device in usbdev_release() usbdev_release() drops its reference to the struct usb_device before draining the list of completed async URBs, but that drain path reads back through the same object: free_async() calls dec_usb_memory_use_count() for any URB whose buffer came from the usbfs mmap() region, and its first statement is bus_to_hcd(ps->dev->bus). After a disconnect the usbfs reference can be the last one, in which case usb_put_dev() frees the device and the subsequent loop reads offset 80 of freed memory and uses the result as a struct usb_hcd *, which hcd_buffer_free_pages() then dereferences. This is reachable by an unprivileged process that has read/write access to a /dev/bus/usb node: mmap() the fd, submit one URB with a buffer inside the mapping, wait for the device to be unplugged, then munmap() and close(). It reproduces on every attempt rather than being a race, because a live MAP_SHARED vma holds a reference on the struct file, so usbdev_release() cannot run until the last vma is gone and the freeing branch of dec_usb_memory_use_count() is always taken. BUG: KASAN: slab-use-after-free in dec_usb_memory_use_count+0x3ae/0x410 Read of size 8 at addr ffff8880122ee050 by task poc/769 CPU: 1 UID: 1000 PID: 769 Comm: poc Tainted: G B 6.12.94 #3 Call Trace: dec_usb_memory_use_count+0x3ae/0x410 free_async+0x2aa/0x4f0 usbdev_release+0x375/0x460 __fput+0x3ea/0xb50 __x64_sys_close+0x86/0x100 Allocated by task 11: usb_alloc_dev+0x55/0xd90 hub_event+0x2524/0x43d0 Freed by task 769: kfree+0x121/0x360 device_release+0xd2/0x280 usb_put_dev+0x23/0x30 usbdev_release+0x2d8/0x460 Release the device reference after the drain loop instead. Nothing between the two points requires it to have been dropped. | |
| Title | usb: usbfs: fix use-after-free of usb_device in usbdev_release() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-04T15:54:28.038Z
Reserved: 2026-08-26T14:34:25.795Z
Link: CVE-2026-80824
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-04T16:18:10.233
Modified: 2026-09-04T16:18:10.233
Link: CVE-2026-80824
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.