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CVE-2026-90367
wifi: mt76: mt7996: hold dev->mt76.mutex while disabling tx worker in SER
Published 2026-09-17 (31 days ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-90367 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
mt7996_mac_reset_work() parked the tx worker and disabled the RX/TX NAPIs before taking dev->mt76.mutex. mt76_worker_disable()/_enable() are plain kthread park/unpark, not refcounted, and __mt76_set_channel() toggles the same worker and the MT76_RESET bit under the mutex. An L1 SER racing a channel switch could therefore have the worker unparked and MT76_RESET cleared while the reset path resets the DMA rings, corrupting descriptors or tokens. Take the mutex before disabling the worker, as mt7915 does.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/net/wireless/mediatek/mt76/mt7996/mac.c
- What this is
- MEDIATEK MT76 WIRELESS LAN DRIVERMAINTAINERS section matched on drivers/net/wireless/mediatek/mt76/ · linux-wireless@vger.kernel.org · Maintained
- Kernel module
- mt7996e
Check it on the machine
grep -wE 'CONFIG_MT76_CORE|CONFIG_MT7996E|CONFIG_WLAN|CONFIG_WLAN_VENDOR_MEDIATEK' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w mt7996ePrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookworm?
- trixieMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armel/rpi, s390x/s390x
- forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- ?
- not established - no Makefile entry for the affected file
- M
- a module where it is built at all; some flavours do not build it
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switches
- CONFIG_MT76_CORE, CONFIG_MT7996E, CONFIG_WLAN, CONFIG_WLAN_VENDOR_MEDIATEK
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-17 (31 days ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.38%, higher than 29.9% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.4 | 6.18.52 | 906ad486ba5c |
| 6.4 | 7.2.6 | 594c4b7f89f9 |
| 6.4 | 7.3 | 6190db312b82 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:AAttack vector, adjacent network
- mt7996_irq_tasklet() handles MT_INT_MCU_CMD, reads MT_MCU_CMD, and on ERROR_MASK (including STOP_DMA) calls mt7996_reset() to queue L1 SER; the racing worker toggle is __mt76_set_channel() from mt76_switch_vif_chanctx() on an 802.11 Channel Switch Announcement. Both legs are WiFi radio-range, not a routable IP protocol.
- AC:LAttack complexity, low
- A radio peer can drive both sides: emit CSA so ieee80211_csa_switch_work() runs mt76_switch_vif_chanctx()/__mt76_set_channel() (unparking the non-refcounted tx_worker under dev->mt76.mutex) and induce firmware L1 SER so mt7996_mac_reset_work() parks that worker before taking the mutex. The MCU channel-switch hold and napi_disable() are a retryable millisecond window.
- PR:NPrivileges required, none
- mt7996_irq_tasklet() consumes MT_MCU_CMD and queues reset_work with no capable() or 802.11 authentication gate; CSA is parsed from beacons/action frames in ieee80211_sta_process_chanswitch() without a host uid. An unauthenticated (SER) or associated (CSA) radio peer needs no Linux privilege.
- UI:NUser interaction, none
- ieee80211_csa_switch_work() applies CSA automatically once the STA is associated, and mt7996_mac_reset_work() runs from the driver workqueue after the MCU IRQ. No local user must write debugfs sys_recovery or issue nl80211 SET_CHANNEL to create the race.
- S:UScope, unchanged
- The corrupted TX DMA descriptors (mt76_dma_queue_reset of q->desc[]) and token IDR (mt7996_tx_token_put()/idr_destroy()) belong to this host's mt7996 driver; the race does not cross a VM, IOMMU, or sandbox authority.
- C:HConfidentiality impact, high
- If __mt76_set_channel() unparks tx_worker while mt7996_mac_reset_work() still runs mt7996_dma_reset() and mt7996_tx_token_put(), the worker can idr_alloc on a destroyed token IDR and DMA-map into q->desc[] being zeroed, a UAF/descriptor confusion that discloses kernel memory.
- I:HIntegrity impact, high
- The same race lets the TX worker write queue head and descriptors (mt76_dma_add_buf) while mt76_dma_queue_reset() clears q->desc[] and mt7996_tx_token_put() destroys the token IDR, a write primitive against DMA-ring and heap token objects suitable for control-flow hijack.
- A:HAvailability impact, high
- Concurrent mt76_dma_tx_cleanup()/mt76_dma_queue_reset() versus a live tx_worker oopses on a freed txwi/skb or wedges the WFDMA rings; the commit's descriptor/token corruption is a kernel crash, so availability is High.