CVE-2026-68194
Received Received - Intake

NULL Pointer Dereference in MediaTek mt76 WiFi 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: 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").

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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-2026-68194
EUVD
EUVD-2026-55295

Affected Vendors & Products

Currently, no data is known.

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is a NULL pointer dereference flaw in the Linux kernel's mt76 WiFi driver, specifically affecting the mt7921 chipset. It occurs when the driver incorrectly processes a TXRX_NOTIFY event on non-MMIO buses like USB or SDIO. The event triggers a call to a NULL function pointer in the RX worker thread, causing a kernel crash.

Detection Guidance

This vulnerability may cause a kernel NULL pointer dereference on non-mmio buses (USB/SDIO) when handling TXRX_NOTIFY events. Detection requires checking kernel logs for NULL pointer dereference errors related to mt7921_mac_tx_free or mt76_queue_tx_cleanup.

Impact Analysis

This vulnerability can cause system instability or crashes when using affected WiFi devices on non-MMIO buses. It may lead to denial-of-service conditions, requiring a system reboot to restore functionality. Users with mt7921-based WiFi adapters connected via USB or SDIO are most at risk.

Mitigation Strategies

Apply the Linux kernel patch that drops TXRX_NOTIFY events on non-mmio buses. Update to a kernel version containing the fix (commit 5683e1488aa9). If immediate patching is not possible, disable affected mt76 USB/SDIO WiFi devices until patched.

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