---
id: "CVE-2026-98765"
kind: "vulnerability"
aliases: ["CVE-2026-98765"]
title: "Linux kernel: USB dummy-hcd gadget unbind can race pending request completions"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["kernel", "linux", "runtime", "usb-gadget"]
not_affected_if: ["default-config"]
published_at: "2026-10-18T16:17:30+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:16:40+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98765", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel: USB dummy-hcd gadget unbind can race pending request completions

The dummy-hcd USB gadget emulator's synchronize routine did not wait for in-flight request completion handlers, so a gadget driver could unbind or unload while a completion callback was still running. The sources do not describe a remote or attacker-controlled trigger; the flaw is a use-after-unbind race in a test/emulation driver.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- unknown

## Fix

- unknown

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98765

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

USB: gadget: dummy-hcd: Fix wait for outstanding request completions

The dummy-hcd driver emulates synchronize_irq() by waiting until its
private callback_usage counter drops to 0 (with the private lock not
held).  This counter is incremented whenever a gadget driver callback
occurs (which requires the private lock to be dropped), but not when a
request completion handler is called.

This is an oversight.  Request completion is triggered by timer
interrupts (emulating device IRQs in a real UDC), and the interrupt
handlers are supposed to have completed when the synchronize_irq()
emulation routine returns -- they aren't supposed to be in the middle
of a completion callback.  If this happens it can lead to a gadget
driver's unbind routine running before all outstanding request
completions have finished, maybe even allowing the gadget driver's
module to be unloaded while a completion handler is still running.

Fix the oversight by incrementing the callback_usage value across
request completion callbacks.

---

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