CVE-2026-98765

Received Received - Intake

Race Condition in Linux Kernel USB Gadget Dummy-HCD Driver

Publication date: 2026-10-18

Last updated on: 2026-10-19

Assigner: kernel.org

Description

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-10-18

Last Modified

2026-10-19

Generated

2026-10-19

AI Q&A

2026-10-18

EPSS Evaluated

N/A

NVD

CVE-2026-98765

EUVD

EUVD-2026-103850

Affected Vendors & Products

Vendor	Product	Version / Range
Linux	Linux	7dbd8f4cabd96db5a50513de9d83a8105a5ffc81
Linux	Linux	7dbd8f4cabd96db5a50513de9d83a8105a5ffc81
Linux	Linux	7dbd8f4cabd96db5a50513de9d83a8105a5ffc81
Linux	Linux	7dbd8f4cabd96db5a50513de9d83a8105a5ffc81
Linux	Linux	7b416b9dac6ede26d4ca0c1a88b448b543623ff3
Linux	Linux	8590bc1da625dd4a589eac0fc3aa3cf4f400424d
Linux	Linux	a867d5b932ac4911d3f8a1e63505061b0c81f889
Linux	Linux	e84b4a008365b7edbd842a063ae28d040a98db25
Linux	Linux	e39b17143a5b5aac81f066d455e5d3a9877eb3ae
Linux	Linux	4f8ae1fcb0dfbb72a7678f81bf01fb7fc85c6715
Linux	Linux	3.2.97
Linux	Linux	3.16.52
Linux	Linux	4.1.46
Linux	Linux	4.4.92
Linux	Linux	4.9.55
Linux	Linux	4.13.6
Linux	Linux	4.14

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability is in the Linux kernel's USB gadget dummy-hcd driver. It involves a race condition where the driver fails to properly wait for all USB request completions before allowing a gadget driver to unbind or be unloaded. The issue occurs because the driver's counter for tracking outstanding callbacks does not account for request completion handlers, potentially leading to module unloading while callbacks are still running.

Detection Guidance

This vulnerability is specific to the Linux kernel's USB gadget dummy-hcd driver and may not have direct network detection methods. Check kernel logs for errors related to USB gadget drivers or dummy-hcd using commands like dmesg | grep dummy-hcd or journalctl -k | grep dummy-hcd.

Impact Analysis

If exploited, this vulnerability could cause system instability or crashes by allowing a gadget driver to be unloaded while its completion handlers are still executing. This might lead to kernel panics, data corruption, or denial-of-service conditions on systems using the dummy-hcd driver.

Compliance Impact

This vulnerability does not directly impact compliance with GDPR, HIPAA, or similar standards. It is a Linux kernel USB gadget driver issue that could lead to race conditions during request completions, potentially causing module unloading while handlers are still running. No evidence suggests direct implications for data protection or privacy compliance.

Mitigation Strategies

Apply the latest kernel updates from your Linux distribution to ensure the dummy-hcd driver fix is included. If immediate patching is not possible, consider disabling the dummy-hcd module using modprobe -r dummy_hcd until the update is applied.

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