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CVE-2026-80933
wifi: mt76: mt7996: validate default EEPROM firmware size
Published 2026-09-11 (37 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-2026-80933 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 | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| 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. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The default EEPROM firmware is parsed and copied as a full EEPROM without checking its length. A truncated file can make the driver read beyond the firmware buffer during variant validation or the fallback copy. Reject files shorter than MT7996_EEPROM_SIZE before parsing or copying the firmware.
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/eeprom.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
- bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64
- ?
- 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
- 2026-09-11 (37 days ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.13%, higher than 2.2% 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 |
|---|---|---|
| 6.2 | 6.6.157 | b4bf67cc0871 |
| 6.2 | 6.12.110 | 127a291f4c80 |
| 6.2 | 6.18.50 | 03b81f015dbb |
| 6.2 | 7.2.4 | 7074ec376982 |
| 6.2 | 7.3 | 653c6e289b13 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
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:LAttack vector, local
- The truncated default EEPROM image is consumed only via request_firmware() on the local PCI probe path (mt7996_pci_probe → mt7996_register_device → mt7996_init_hardware → mt7996_eeprom_init → mt7996_eeprom_check_or_use_default); WiFi frames, network protocols, and USB traffic never reach this parser.
- AC:LAttack complexity, low
- A non-empty file shorter than MT7996_EEPROM_SIZE (7680 bytes) deterministically over-reads: variant validation indexes fw->data at MT_EE_WIFI_CONF, and a crafted WIFI_CONF that fails the match (or the common use_default fallback) takes memcpy(eeprom, fw->data, 7680) with no race or layout luck.
- PR:LPrivileges required, low
- The parse path has no capability check, and default EEPROM blobs live under /lib/firmware/mediatek/mt7996/ and vendor firmware partitions on OpenWrt/AP/Android Filogic deployments that are often writable by non-root system or OTA accounts, so a low-privileged local user can position the truncated image.
- UI:NUser interaction, none
- Once the truncated EEPROM firmware file is in place, request_firmware() and the subsequent parse/copy run automatically during driver probe at boot or module bind; no victim action such as opening a device node or mounting a filesystem is required.
- S:UScope, unchanged
- The out-of-bounds read and the EEPROM/MCU state it poisons remain inside the host kernel and the local MT7996 device; this is not a VM escape, IOMMU bypass, or other cross-authority breakout.
- C:HConfidentiality impact, high
- memcpy(..., 7680) and mt7996_eeprom_parse_stream() read far past the firmware buffer into eeprom.data, which is then used as the interface MAC, exposed via the 0400 debugfs eeprom blob, and uploaded to the MCU—an unbounded kernel-memory disclosure, not a few-byte leak.
- I:HIntegrity impact, high
- The fallback memcpy writes the over-read kernel memory into the live 7680-byte EEPROM object that then drives MAC/capability configuration and mt7996_mcu_set_eeprom() programming of the WiFi 7 MCU, so attacker-influenced data corrupts kernel and device control state; memory-corruption copies are rated High.
- A:HAvailability impact, high
- Firmware buffers are vmalloc/vmap allocations with guard pages, so a 7680-byte over-read from a short file reliably faults into an unmapped page and oopses or panics the kernel during probe of MT7996/MT7992/MT7990 hardware.