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CVE-2026-74409
wifi: rtw89: add bounds check on firmware mac_id in link lookup
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-2026-74409 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
The mac_id field in RX descriptors is 8 bits wide (0-255), but assoc_link_on_macid[] has only RTW89_MAX_MAC_ID_NUM (128) entries. While the driver currently assigns mac_id values below 128, the descriptor value comes from firmware and is not validated before use as an array index. Add a defensive bounds check in rtw89_assoc_link_rcu_dereference() to guard against out-of-range firmware values.
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/realtek/rtw89/core.h
- What this is
- REALTEK WIRELESS DRIVER (rtw89)MAINTAINERS section matched on drivers/net/wireless/realtek/rtw89/ · linux-wireless@vger.kernel.org · Maintained
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid?
- ?
- not established - no Makefile entry for the affected file
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.
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
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 |
|---|---|---|
| 6.14 | 6.18.40 | ad445de67359 |
| 6.14 | 7.1.5 | 920101305e76 |
| 6.14 | 7.2 | 6d88244bb129 |
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 bug is reached when rtw89 processes WiFi RX descriptors or firmware C2H events whose mac_id is taken from device firmware after over-the-air frame reception; per kernel CNA guidance, WiFi driver bugs exploitable via injected/received 802.11 frames are Adjacent, not local or physical.
- AC:LAttack complexity, low
- An adjacent attacker can repeatedly send 802.11 frames (client or softAP role) to drive normal PCI/USB RX and firmware notification paths; no rare victim state, secret, or uncontrollable memory layout is required beyond having WiFi active on an affected rtw89 device.
- PR:NPrivileges required, none
- Exploitation requires only radio-range WiFi access to a victim using the rtw89 driver; the attacker needs no local shell account, kernel capability, or init-namespace root on the target system.
- UI:NUser interaction, none
- No victim interaction is required at exploitation time; once the interface is operating, malicious over-the-air traffic alone can populate firmware RX/C2H metadata with an out-of-range mac_id and hit the vulnerable lookup.
- S:UScope, unchanged
- Impact is confined to kernel/driver memory corruption and crashes on the host running rtw89; it does not cross a VM, container, or IOMMU security boundary into another authority.
- C:HConfidentiality impact, high
- Using an unvalidated firmware mac_id (up to 255, or wider in C2H) as an index performs an out-of-bounds read of assoc_link_on_macid[], interpreting adjacent rtw89_dev fields as a station pointer and enabling further unintended kernel memory reads.
- I:HIntegrity impact, high
- The out-of-bounds pointer is dereferenced and used for writes and callbacks (e.g., tid_rx_stats updates, PS flag changes, ieee80211_sta_ps_transition/uapsd), giving memory corruption primitives that could be developed into arbitrary kernel write or code execution.
- A:HAvailability impact, high
- Dereferencing attacker-influenced out-of-bounds pointers from assoc_link_on_macid[] can immediately trigger kernel oops/panic or hang during RX processing on production WiFi clients, softAPs, and hotspots using affected Realtek rtw89 hardware.