CVE-2026-80824 - Vulnerability Details

- usb: usbfs: fix use-after-free of usb_device in usbdev_release()

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.

Published: 2026-09-04

Score: n/a

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The vulnerability is a use‑after‑free in the usbfs subsystem of the Linux kernel. An unprivileged user with read/write access to a /dev/bus/usb device can map the device’s buffer, trigger a disconnect, and cause the kernel to read freed memory while releasing the usb_device structure. This kernel memory corruption can lead to arbitrary code execution or a denial of service.

Affected Systems

All Linux kernel releases that expose the usbfs implementation are potentially affected because the CNA vendor list lists Linux:Linux and no specific versions are excluded. The issue appears in kernels that support /dev/bus/usb nodes and use usbfs mmaping for user‑space URB buffers. Systems running recent kernels should verify whether the patch that rearranges the release timing has been applied.

Risk and Exploitability

The CVSS score is not supplied, and the vulnerability is not listed in CISA’s KEV catalog. No EPSS score is available, but the exploit path requires only local privileges and can be executed deterministically; it does not rely on a race condition. Consequently the risk for systems with exposed USB devices is high, especially if an attacker can obtain access to the device node.

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
`f7d34b445abc00e979b7cf36b9580ac3d1a47cd8`	affected	< 0a960b88c5979f853019d4dc4957dfbeeb193440
`f7d34b445abc00e979b7cf36b9580ac3d1a47cd8`	affected	< 96f5520fc9a5e4bbf77ac93c9d5ce502f597e6cf
`f7d34b445abc00e979b7cf36b9580ac3d1a47cd8`	affected	< bd4bffc621a8cb2f4d9ed9b6447415de524a3bef
`f7d34b445abc00e979b7cf36b9580ac3d1a47cd8`	affected	< 65879e0a452ca2a234b9475e0c11aff7a4343738
`f7d34b445abc00e979b7cf36b9580ac3d1a47cd8`	affected	< b3cde26a66b04f1d90ed0b675899c88b4e49d424
`f7d34b445abc00e979b7cf36b9580ac3d1a47cd8`	affected	< 5f08c45bdcfd28d1171de38c5ef29fc89a76eedc
`f7d34b445abc00e979b7cf36b9580ac3d1a47cd8`	affected	< 7f0278e474c4d1c4457974ff1137cc385c944ab3
`f7d34b445abc00e979b7cf36b9580ac3d1a47cd8`	affected	< 47a7f98fbb5006d46d15a3a210ffdc61448a4f19
`f7d34b445abc00e979b7cf36b9580ac3d1a47cd8`	affected	< 0dd68b5d01d022fc9c5e71c82a82b0a94d3d0671

Linux

affected

Version	Status	Constraints
`4.6`	affected	—
`0`	unaffected	< 4.6
`5.10.269`	unaffected	≤ 5.10.*
`5.15.220`	unaffected	≤ 5.15.*
`6.1.187`	unaffected	≤ 6.1.*
`6.6.156`	unaffected	≤ 6.6.*
`6.12.108`	unaffected	≤ 6.12.*
`6.18.49`	unaffected	≤ 6.18.*
`7.1.13`	unaffected	≤ 7.1.*
`7.2.3`	unaffected	≤ 7.2.*
`7.3-rc1`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[f7d34b445abc00e979b7cf36b9580ac3d1a47cd8,0a960b88c5979f853019d4dc4957dfbeeb193440)`	affected	code_commit	—
`[f7d34b445abc00e979b7cf36b9580ac3d1a47cd8,96f5520fc9a5e4bbf77ac93c9d5ce502f597e6cf)`	affected	code_commit	—
`[f7d34b445abc00e979b7cf36b9580ac3d1a47cd8,bd4bffc621a8cb2f4d9ed9b6447415de524a3bef)`	affected	code_commit	—
`[f7d34b445abc00e979b7cf36b9580ac3d1a47cd8,65879e0a452ca2a234b9475e0c11aff7a4343738)`	affected	code_commit	—
`[f7d34b445abc00e979b7cf36b9580ac3d1a47cd8,b3cde26a66b04f1d90ed0b675899c88b4e49d424)`	affected	code_commit	—
`[f7d34b445abc00e979b7cf36b9580ac3d1a47cd8,5f08c45bdcfd28d1171de38c5ef29fc89a76eedc)`	affected	code_commit	—
`[f7d34b445abc00e979b7cf36b9580ac3d1a47cd8,7f0278e474c4d1c4457974ff1137cc385c944ab3)`	affected	code_commit	—
`[f7d34b445abc00e979b7cf36b9580ac3d1a47cd8,47a7f98fbb5006d46d15a3a210ffdc61448a4f19)`	affected	code_commit	—
`[f7d34b445abc00e979b7cf36b9580ac3d1a47cd8,0dd68b5d01d022fc9c5e71c82a82b0a94d3d0671)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`4.6`	affected	generic	—
`[0,4.6)`	unaffected	semver	—
`[5.10.269,5.10.*]`	unaffected	generic	—
`[5.15.220,5.15.*]`	unaffected	generic	—
`[6.1.187,6.1.*]`	unaffected	generic	—
`[6.6.156,6.6.*]`	unaffected	generic	—
`[6.12.108,6.12.*]`	unaffected	generic	—
`[6.18.49,6.18.*]`	unaffected	generic	—
`[7.1.13,7.1.*]`	unaffected	generic	—
`[7.2.3,7.2.*]`	unaffected	generic	—
`[7.3-rc1,*]`	unaffected	generic	—

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Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Update the Linux kernel to a version that includes the fix that moves the usb_device reference release past the drain loop.
If updating is not yet possible, limit access to /dev/bus/usb nodes to privileged users or disable the usbfs interface entirely.
Monitor kernel logs for KASAN or panic messages indicating memory corruption from usbfs use‑after‑free.

Generated by OpenCVE AI on September 4, 2026 at 20:58 UTC.

Tracking

Sign in to view the affected projects.

Advisories

Source	ID	Title
Debian DLA	DLA-4777-1	linux security update

No CVSS v4.0

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00195.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/0a960b88c5979f853019d4dc4957dfbeeb193440
https://git.kernel.org/stable/c/0dd68b5d01d022fc9c5e71c82a82b0a94d3d0671
https://git.kernel.org/stable/c/47a7f98fbb5006d46d15a3a210ffdc61448a4f19
https://git.kernel.org/stable/c/5f08c45bdcfd28d1171de38c5ef29fc89a76eedc
https://git.kernel.org/stable/c/65879e0a452ca2a234b9475e0c11aff7a4343738
https://git.kernel.org/stable/c/7f0278e474c4d1c4457974ff1137cc385c944ab3
https://git.kernel.org/stable/c/96f5520fc9a5e4bbf77ac93c9d5ce502f597e6cf
https://git.kernel.org/stable/c/b3cde26a66b04f1d90ed0b675899c88b4e49d424
https://git.kernel.org/stable/c/bd4bffc621a8cb2f4d9ed9b6447415de524a3bef

History

Fri, 04 Sep 2026 21:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-416

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		https://git.kernel.org/stable/c/0a960b88c5979f853019d4dc4957dfbeeb193440 https://git.kernel.org/stable/c/0dd68b5d01d022fc9c5e71c82a82b0a94d3d0671 https://git.kernel.org/stable/c/47a7f98fbb5006d46d15a3a210ffdc61448a4f19 https://git.kernel.org/stable/c/5f08c45bdcfd28d1171de38c5ef29fc89a76eedc https://git.kernel.org/stable/c/65879e0a452ca2a234b9475e0c11aff7a4343738 https://git.kernel.org/stable/c/7f0278e474c4d1c4457974ff1137cc385c944ab3 https://git.kernel.org/stable/c/96f5520fc9a5e4bbf77ac93c9d5ce502f597e6cf https://git.kernel.org/stable/c/b3cde26a66b04f1d90ed0b675899c88b4e49d424 https://git.kernel.org/stable/c/bd4bffc621a8cb2f4d9ed9b6447415de524a3bef

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-09-04T15:54:28.038Z

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

Updated: 2026-09-05T00:15:13Z

Weaknesses

CWE-416
Use After Free

Impact

Affected Systems

Risk and Exploitability

Tracking

Subscriptions

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