CVE-2026-68363
Received Received - Intake

Use-After-Free in Linux Kernel ath9k USB HIF Driver

Publication date: 2026-08-10

Last updated on: 2026-08-10

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: wifi: ath9k: hif_usb: don't dereference hif_dev after re-arming firmware request ath9k_hif_request_firmware() re-arms an asynchronous firmware load via request_firmware_nowait(), passing hif_dev as the completion context, and then still dereferences hif_dev: dev_info(&hif_dev->udev->dev, "ath9k_htc: Firmware %s requested\n", hif_dev->fw_name); The re-armed callback ath9k_hif_usb_firmware_cb() runs on the "events" workqueue and, when the firmware is missing, walks the retry chain into ath9k_hif_usb_firmware_fail() -> complete_all(&hif_dev->fw_done). That releases the wait_for_completion(&hif_dev->fw_done) in a concurrent ath9k_hif_usb_disconnect(), which then kfree()s hif_dev. The trailing dev_info() in the frame that re-armed the request can therefore read freed memory (hif_dev->udev, the first field of struct hif_device_usb): BUG: KASAN: slab-use-after-free in ath9k_hif_request_firmware Read of size 8 ... by task kworker/... ath9k_hif_request_firmware ath9k_hif_usb_firmware_cb drivers/net/wireless/ath/ath9k/hif_usb.c:1247 request_firmware_work_func Allocated by ...: ath9k_hif_usb_probe drivers/net/wireless/ath/ath9k/hif_usb.c Freed by ...: ath9k_hif_usb_disconnect -> kfree drivers/net/wireless/ath/ath9k/hif_usb.c The fw_done barrier only makes disconnect wait for the firmware chain to *terminate*; it does not protect the outer ath9k_hif_request_firmware() frame that re-armed the request and keeps touching hif_dev afterwards. Drop the post-request dev_info(): it is the only use of hif_dev after the async request is armed, and it is purely informational (the dev_err() on the failure path runs only when request_firmware_nowait() did not arm a callback, so hif_dev is still alive there). This was first reported by syzbot as a single, non-reproduced crash that was later auto-obsoleted, and was independently rediscovered by the reFuzz fuzzer, which produced a C reproducer (USB-gadget connect/disconnect of an ath9k_htc device whose firmware download fails). The vulnerable code is unchanged and still present in v7.1-rc6, where the slab-use-after-free reproduces under KASAN once the (sub-microsecond) race window is widened.

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Meta Information

Published
2026-08-10
Last Modified
2026-08-10
Generated
2026-08-10
AI Q&A
2026-08-10
EPSS Evaluated
N/A
NVD
CVE-2026-68363
EUVD
EUVD-2026-55464

Affected Vendors & Products

Currently, no data is known.

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a use-after-free vulnerability in the Linux kernel's ath9k wireless driver. It occurs when the firmware loading process is re-armed asynchronously while the driver still tries to access freed memory. Specifically, the driver requests firmware and then continues to use a pointer to a device structure that may have been freed by a concurrent disconnect operation.

Detection Guidance

This vulnerability is specific to the Linux kernel's ath9k USB WiFi driver and involves a use-after-free condition during firmware handling. Detection requires kernel logs showing KASAN errors or slab-use-after-free messages related to ath9k_hif_request_firmware. Check system logs with: dmesg | grep -i kasan or dmesg | grep -i ath9k. If the race condition occurs, you may see crashes during USB device disconnects while firmware loading fails.

Impact Analysis

This vulnerability could cause system crashes or instability if exploited. An attacker with physical access could potentially trigger the race condition by rapidly connecting and disconnecting an ath9k_htc USB WiFi device, leading to kernel memory corruption. It may also enable privilege escalation if combined with other exploits.

Mitigation Strategies

Apply the latest Linux kernel security updates that patch this issue. If immediate patching is not possible, disable the ath9k_htc driver by blacklisting it: echo 'blacklist ath9k_htc' > /etc/modprobe.d/blacklist-ath9k.conf and reboot. Alternatively, avoid using affected ath9k USB WiFi devices until patched.

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