# CVE-2026-80824: usb: usbfs: fix use-after-free of usb_device in usbdev_release()

> A use-after-free in the Linux kernel USB subsystem allows local attackers to execute code or escalate privileges via crafted USB operations.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-99530, BELL-CVE-2026-80824, DEBIAN-CVE-2026-80824, GHSA-j9hx-p692-x42g, UBUNTU-CVE-2026-80824

## What is CVE-2026-80824?

CVE-2026-80824 is an use after free vulnerability in Linux, published on 4 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

## Which versions are affected by CVE-2026-80824?


## How do I fix CVE-2026-80824?

Apply the vendor's patch.

## Is CVE-2026-80824 being exploited?

There is no known exploitation of CVE-2026-80824 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80824 and fix it if it is affected.

What it is: CVE-2026-80824 is an use after free vulnerability in Linux, published on 4 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-80824 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-80824/ (Markdown: https://insights.sbomify.com/CVE-2026-80824/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80824
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80824
- OSV: https://osv.dev/vulnerability/CVE-2026-80824

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80824/
Summaries are generated and may contain mistakes; the official description above is the record.