CVE-2026-68194 wifi: mt76: mt7921: drop TXRX_NOTIFY on non-mmio buses
A null pointer dereference in the Linux kernel mt7921 WiFi driver causes a system crash when processing specific packets on USB or SDIO buses.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-68194?
CVE-2026-68194 is a vulnerability in Linux, published on 10 Aug 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: mt76: mt7921: drop TXRX_NOTIFY on non-mmio buses
PKT_TYPE_TXRX_NOTIFY is an mmio-only event, but mt7921_rx_check() and mt7921_queue_rx_skb() dispatch it to mt7921_mac_tx_free() on every bus. mt7921_mac_tx_free() cleans the DMA tx queues with mt76_queue_tx_cleanup(), which calls queue_ops->tx_cleanup(). Only the mmio queue ops implement that callback; on USB and SDIO it is NULL, so a TXRX_NOTIFY there calls a NULL pointer in the RX worker:
BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:0x0 Call Trace: mt7921_mac_tx_free+0x64/0x310 [mt7921_common] mt7921_rx_check+0x5f/0xf0 [mt7921_common] mt76u_rx_worker+0x1b9/0x620 [mt76_usb]
Drop the event on non-mmio buses via mt76_is_mmio(), as in commit 5683e1488aa9 ("wifi: mt76: connac: do not check WED status for non-mmio devices").
Which versions are affected by CVE-2026-68194?
How do I fix CVE-2026-68194?
Apply the vendor's patch.
Is CVE-2026-68194 being exploited?
There is no known exploitation of CVE-2026-68194 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68194, DEBIAN-CVE-2026-68194, GHSA-qgch-244m-5hcp, UBUNTU-CVE-2026-68194.