CVE-2026-80947 wifi: rtl8xxxu: fix use-after-free from rx_urb_wq on stop
A use-after-free vulnerability in the Linux kernel rtl8xxxu WiFi driver allows attackers to cause denial of service or execute code via a race condition during device disconnection.
- 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
What is CVE-2026-80947?
CVE-2026-80947 is a high-severity use after free vulnerability in Linux, published on 11 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:
wifi: rtl8xxxu: fix use-after-free from rx_urb_wq on stop
rtl8xxxu arms rx_urb_wq from the RX completion path: rtl8xxxu_rx_complete() hands the URB to rtl8xxxu_queue_rx_urb(), which queues it on rx_urb_pending_list and, once the list grows past RTL8XXXU_RX_URB_PENDING_WATER, schedules rx_urb_wq. The worker rtl8xxxu_rx_urb_work() drains rx_urb_pending_list, recovers priv through container_of, and resubmits each URB through rtl8xxxu_submit_rx_urb(), which anchors it on rx_anchor and dereferences priv->udev.
rtl8xxxu_stop() cancels the sibling work items (c2hcmd_work, ra_watchdog, update_beacon_work) but never cancels rx_urb_wq, so a worker armed during the last burst of RX traffic can run rtl8xxxu_rx_urb_work() after rtl8xxxu_disconnect() has called ieee80211_free_hw(), which frees priv, producing a use-after-free. The window opens under active RX traffic (pending count above the watermark) followed by a disconnect.
There are two teardown races to close:
* rtl8xxxu_queue_rx_urb() decided whether to enqueue under rx_urb_lock but called schedule_work() after dropping the lock. A completion that observed shutdown == false and released the lock could then call schedule_work() after rtl8xxxu_stop() had set shutdown and cancel_work_sync() had already returned, arming the worker to run after the teardown. Move schedule_work() under the same !shutdown branch so the arming decision is atomic with the shutdown check.
* rtl8xxxu_rx_urb_work() anchors every URB it drained back onto rx_anchor through rtl8xxxu_submit_rx_urb(). A worker still running when usb_kill_anchored_urbs(&priv->rx_anchor) returned would submit a URB that escaped the kill. In rtl8xxxu_stop(), call cancel_work_sync(&priv->rx_urb_wq) before the kill so the worker is drained first.
After priv->shutdown is set under rx_urb_lock, completions can no longer queue rx_urb_wq. cancel_work_sync() then drains the last queued or running worker, and the following usb_kill_anchored_urbs() kills the URBs it may have submitted.
rtl8xxxu_disconnect() is covered because ieee80211_unregister_hw() guarantees .stop() runs for a live interface before ieee80211_free_hw() frees priv. The probe error path needs no cancel: rx_urb_wq is INIT_WORK()'d there but cannot have been scheduled, since no URB is submitted before ieee80211_register_hw() succeeds.
This bug was found by static analysis.
Which versions are affected by CVE-2026-80947?
How do I fix CVE-2026-80947?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-80947 being exploited?
There is no known exploitation of CVE-2026-80947 in the wild and no public exploit code.
Sources
Also known as AZL-100298, BELL-CVE-2026-80947, DEBIAN-CVE-2026-80947, GHSA-g2ww-fvxp-525w, UBUNTU-CVE-2026-80947.