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CVE-2026-90399
wifi: ath12k: fix stride mismatch in mac_phy_caps_parse()
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-2026-90399 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
Currently, in ath12k_wmi_mac_phy_caps_parse(), kzalloc() sizes the mac_phy_caps buffer as tot_phy_id * len, where len is clamped to min(firmware_len, sizeof(struct ath12k_wmi_mac_phy_caps_params)). The subsequent memcpy() destination advances by sizeof(full struct) per slot via C pointer arithmetic, not by the clamped len. When firmware sends short TLVs, the second and later slots are written past the end of the allocation. The reader in ath12k_pull_mac_phy_cap_svc_ready_ext() also indexes the buffer with full-struct pointer arithmetic, so the allocation must match that stride. Fix by using kzalloc_objs(), which derives the element size from the pointer type, making allocation size and pointer stride provably consistent regardless of what len the firmware provides. Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3
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/ath/ath12k/wmi.c
- What this is
- QUALCOMM ATH12K WIRELESS DRIVERMAINTAINERS section matched on drivers/net/wireless/ath/ath12k/ · linux-wireless@vger.kernel.org · Supported
- Kernel module
- ath12k
Check it on the machine
grep -wE 'CONFIG_ATH12K|CONFIG_WLAN|CONFIG_WLAN_VENDOR_ATH' /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 ath12kPrints 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_ATH12K, CONFIG_WLAN, CONFIG_WLAN_VENDOR_ATH
- 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
- 8.4 high
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.18%, higher than 7.6% 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 |
|---|---|---|
| 6.3 | 6.12.110 | d3355e0fdbbf |
| 6.3 | 6.18.52 | b9a5d12cbdeb |
| 6.3 | 7.2.6 | 26f8f87f0a55 |
| 6.3 | 7.3 | 4c6eb712a91f |
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 malformed bytes are WMI_TAG_MAC_PHY_CAPABILITIES TLVs inside WMI_SERVICE_READY_EXT_EVENTID, DMA'd from the ath12k firmware Copy Engine (ath12k_ce_recv_process_cb → ath12k_htc_rx_completion_handler → ath12k_wmi_op_rx → ath12k_service_ready_ext_event → ath12k_wmi_mac_phy_caps_parse). That is PCIe/AHB host-firmware WMI, not an 802.11 frame.
- AC:LAttack complexity, low
- Firmware sets tot_phy_id via fls(phy_id_map) in ath12k_wmi_hw_mode_caps_parse and the TLV length (no min_len for WMI_TAG_MAC_PHY_CAPABILITIES). Any tot_phy_id>=2 with len < sizeof(struct ath12k_wmi_mac_phy_caps_params) makes memcpy of slot 1+ land past the tot_phy_id*len kzalloc; no race or layout lottery.
- PR:NPrivileges required, none
- The CE/HTC WMI receive path has no capable() or authentication check; ath12k_service_ready_ext_event parses whatever firmware posts. A compromised or malicious WCN7850/QCN9274 firmware needs no Linux account.
- UI:NUser interaction, none
- ath12k_core_start() blocks in ath12k_wmi_wait_for_service_ready() during probe and crash recovery (ath12k_core_reconfigure_on_crash); the overflow runs when that event arrives, with no victim ioctl, mount, or iface config.
- S:UScope, unchanged
- The GFP_ATOMIC heap overflow is in the host kernel's mac_phy_caps buffer allocated by ath12k_wmi_mac_phy_caps_parse. Impact stays in that kernel; this is not a KVM/Xen escape or IOMMU DMA-remapping bypass.
- C:HConfidentiality impact, high
- memcpy writes firmware-chosen payloads at full-struct strides past a short tot_phy_id*len object, and ath12k_wmi_save_all_mac_phy_info()/ath12k_pull_mac_phy_cap_svc_ready_ext() then read that heap with the same stride, giving a high-confidentiality primitive from adjacent objects.
- I:HIntegrity impact, high
- Each overflowing slot is an out-of-bounds write of firmware-controlled contents (up to just-under-sizeof(struct ath12k_wmi_mac_phy_caps_params) bytes) into the kernel heap, enabling adjacent-object corruption and control-flow hijack.
- A:HAvailability impact, high
- The same OOB write, and the later full-struct walk of the undersized mac_phy_caps buffer in ath12k_wmi_save_all_mac_phy_info(), can smash heap metadata or adjacent pointers and oops/panic the kernel.