CVE-2026-90399 wifi: ath12k: fix stride mismatch in mac_phy_caps_parse()
A stride mismatch in the ath12k WiFi driver allows out-of-bounds writes when processing short firmware TLVs, potentially leading to memory corruption or crashes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90399?
CVE-2026-90399 is a high-severity memory corruption vulnerability in Linux, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
wifi: ath12k: fix stride mismatch in mac_phy_caps_parse()
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
Which versions are affected by CVE-2026-90399?
How do I fix CVE-2026-90399?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-90399 being exploited?
There is no known exploitation of CVE-2026-90399 in the wild and no public exploit code.
Sources
Also known as AZL-102621, BELL-CVE-2026-90399, DEBIAN-CVE-2026-90399, GHSA-2568-8wcm-qh64, UBUNTU-CVE-2026-90399.