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CVE-2026-74323
wifi: mt76: mt7996: Fix possible token leak in mt7996_tx_prepare_skb()
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-74323 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 | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
If link_conf or link_sta lookup fails in mt7996_tx_prepare_skb routine, mt7996 driver leaks an already allocated tx token. Fix the issue releasing the token in case of error.
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
drivers/net/wireless/mediatek/mt76/tx.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.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- 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
- M
- a module where it is built at all; some flavours do not build it
- 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
- 2026-08-15 (2 months 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 |
|---|---|---|
| 6.18 | 6.18.40 | 06e65d6cf804 |
| 6.18 | 7.1.5 | fa0e9aa92a7b |
| 6.18 | 7.2 | 831074096d04 |
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
- The flaw is in mt7996 TX preparation for EAPOL frames on MLO stations; a nearby WiFi attacker can trigger WPA authentication/rekey traffic that drives this driver TX path on APs, routers, and clients using MediaTek mt7996 hardware.
- AC:LAttack complexity, low
- An attacker can repeatedly initiate or tear down MLO associations and EAPOL exchanges to hit the narrow window where link_conf/link_sta are NULL during TX, reliably leaking tokens without depending on uncontrollable system state.
- PR:NPrivileges required, none
- Exploitation requires only an unauthenticated adjacent WiFi peer initiating or disrupting MLO WPA handshakes that cause EAPOL transmission; no local account, capability, or init-namespace root access is needed on the victim.
- UI:NUser interaction, none
- No victim user action such as opening files or clicking prompts is required; the attacker alone can generate the authentication traffic needed to reach the vulnerable EAPOL TX path.
- S:UScope, unchanged
- Impact is confined to the kernel wireless subsystem on the affected host (token exhaustion and potential memory corruption); it does not cross VM, container, or IOMMU security boundaries.
- C:HConfidentiality impact, high
- Leaked tokens leave stale idr entries pointing at txwi_cache structures that dma.c returns to the free pool, enabling reuse of the same cache while orphaned entries retain dangling skb pointers that can be dereferenced on later token operations.
- I:HIntegrity impact, high
- Reusing txwi_cache buffers still referenced by leaked token IDs can corrupt in-flight TX metadata and skb associations, providing a plausible path to controlled memory corruption and kernel code execution beyond simple resource loss.
- A:HAvailability impact, high
- Each leak permanently consumes one of 16384 TX tokens; sustained triggering exhausts the pool, invokes __mt76_set_tx_blocked(), and halts all wireless transmission on the interface, constituting a repeatable denial of service.