CVE-2026-80824
Received Received - Intake

Use-After-Free in Linux Kernel USBFS Driver

Publication date: 2026-09-04

Last updated on: 2026-09-04

Assigner: kernel.org

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.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-09-04
Last Modified
2026-09-04
Generated
2026-09-04
AI Q&A
2026-09-04
EPSS Evaluated
N/A
NVD
CVE-2026-80824
EUVD
EUVD-2026-71274

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel 6.12.94

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This is a use-after-free vulnerability in the Linux kernel's USB filesystem (usbfs) implementation. It occurs when usbdev_release() drops its reference to a USB device before draining completed asynchronous URBs (USB Request Blocks). The drain path tries to access the freed device memory, leading to a slab-use-after-free condition. An unprivileged user with read/write access to a /dev/bus/usb node can exploit this by mapping the file, submitting an URB with a buffer in the mapping, unplugging the device, and then unmapping and closing the file.

Detection Guidance

This vulnerability is specific to the Linux kernel's USB subsystem and requires local access to a vulnerable system. Detection involves checking the kernel version and looking for signs of exploitation in system logs. Use 'uname -a' to check the kernel version and 'dmesg' or 'journalctl -k' to inspect for KASAN errors or slab-use-after-free messages related to usbdev_release.

Impact Analysis

An attacker could exploit this to cause a denial-of-service (system crash) or potentially execute arbitrary code with kernel privileges. The vulnerability is triggered by a local unprivileged user with access to USB devices, making it a local privilege escalation risk. Successful exploitation requires specific steps involving USB device interaction and memory manipulation.

Mitigation Strategies

Immediately update the Linux kernel to a patched version where this issue is resolved. If updating is not immediately possible, restrict access to /dev/bus/usb nodes by unprivileged users to reduce exposure. Monitor system logs for signs of exploitation attempts.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-80824. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart