Medium [CVE-2026-68193] Linux kernel: mt76/mt7925 Wi-Fi driver NULL pointer dereference leads to denial of service
This medium-severity Red Hat Linux advisory covers CVE-2026-68193 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux for NVIDIA 26, Red Hat package: kernel.
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Summary
In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7925: drop TXRX_NOTIFY on non-mmio buses PKT_TYPE_TXRX_NOTIFY is an mmio-only event, but mt7925_rx_check() and mt7925_queue_rx_skb() dispatch it to mt7925_mac_tx_free() on every bus. mt7925_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 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: mt7925_mac_tx_free+0x58/0x350 [mt7925_common] mt7925_rx_check+0xe2/0x130 [mt7925_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").
The mt7925 Wi-Fi driver incorrectly dispatches a memory-mapped I/O (MMIO) specific event to non-MMIO buses, such as USB. This improper handling leads to a NULL pointer dereference when attempting to clean up DMA transmit queues.
A remote attacker could exploit this vulnerability by sending specially crafted Wi-Fi packets, causing a system crash and resulting in a denial of service. Red Hat severity: Important — CVSS 5.3 (CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-476.
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 1 hour 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 1 hour 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 1 hour ago·verify at source
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