Medium [CVE-2026-68194] Linux Kernel mt76 WiFi Driver: Denial of Service via NULL Pointer Dereference
This medium-severity Red Hat Linux advisory covers CVE-2026-68194.
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Summary
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").
This can lead to a kernel NULL pointer dereference, causing a system crash and resulting in a Denial of Service (DoS). Red Hat severity: Important — CVSS 4.8 (CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-476. Red Hat lists Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat Enterprise Linux for NVIDIA 26; Red Hat OpenShift Container Platform 4 as not affected.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
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