CVE-2026-90345 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: brcmfmac: fix P2P action frame handling without device vif
Some P2P action frame paths assume the P2P device vif is always available. That is not true when userspace sends non-P2P public action frames through the primary interface, or when action-frame abort runs after the P2P device vif has not been created.
Fall back to the primary vif when aborting an action frame without a P2P device vif, and guard P2P device saved IE access before using it for peer channel search.
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Analysis
by VulDB Data Team • 09/17/2026
The Broadcom brcmfmac wireless driver in the Linux kernel contains a logic flaw related to the handling of Wi-Fi Protected Setup (WPS) Peer-to-Peer action frames when the dedicated virtual interface for P2P operations is not present. In normal operation, the driver creates a specific virtual interface structure known as the device vif to manage P2P-specific communication channels and state machines. However, this assumption that such an interface always exists during certain frame processing paths proves incorrect under specific operational conditions. Specifically, when userspace applications send non-P2P public action frames through the primary network interface, or when a request to abort ongoing action frame processes occurs after the P2P device vif has not been successfully created, the driver fails to account for this absence. This oversight leads to improper handling of control messages that are critical for maintaining stable wireless connections and adhering to IEEE 802.11 standards regarding management frame processing.
The technical root cause lies in the lack of defensive programming within the action frame abort logic and peer channel search routines. The code attempts to access saved Information Elements associated with the P2P device vif without first verifying that this structure is valid or allocated. When the pointer to this non-existent interface is dereferenced, it results in a null pointer dereference vulnerability. This type of memory corruption typically manifests as a kernel panic or system crash, effectively causing a denial of service for the host machine and any connected clients relying on that wireless adapter. The flaw highlights a gap in input validation where the driver assumes a specific configuration state without confirming its existence at runtime, which is a common pattern in complex network stack implementations where interface states can change dynamically based on user requests or hardware events.
From an operational impact perspective, this vulnerability allows for local denial of service attacks if triggered by privileged userspace processes that control the wireless subsystem. An attacker with access to the system and appropriate permissions could craft specific malformed action frames or trigger state transitions that force the driver into a code path where the P2P device vif is missing. The resulting kernel crash would disrupt all network connectivity provided by that interface, potentially affecting critical services depending on how essential this wireless link is to the host's operation. While remote exploitation via unauthenticated network traffic is less likely due to the requirement for userspace interaction or specific local state conditions, the severity remains significant because it compromises system stability and availability without requiring elevated privileges beyond standard user access if the triggering action can be initiated by a non-root process interacting with the wireless driver interface.
To mitigate this risk, the resolution involves implementing robust fallback mechanisms within the brcmfmac driver code. The fix ensures that when aborting an action frame in the absence of a dedicated P2P device vif, the system gracefully falls back to using the primary virtual interface for handling these control operations rather than crashing. Additionally, the patch introduces explicit guards before accessing saved Information Elements intended for peer channel searches, ensuring that memory is only accessed if the corresponding data structures are confirmed to be present and valid. This aligns with best practices in secure coding by validating pointers and state conditions prior to dereferencing or processing sensitive kernel data.
This vulnerability maps directly to CWE-476, which describes a NULL Pointer Dereference error where software attempts to use an object reference that points to null memory. In the context of attack classification, this flaw can be leveraged in scenarios falling under MITRE ATT&CK technique T1529, System Shutdown or Reboot, as crashing the kernel effectively shuts down the system's networking capabilities until a reboot occurs. Furthermore, it relates to CWE-672, Use of Undefined Variable, Pointer, or Reference, specifically regarding the assumption that allocated resources persist throughout their expected lifecycle without explicit existence checks. Remediation requires applying the upstream Linux kernel patch that addresses these specific code paths in the brcmfmac driver, ensuring that all action frame handling routines include proper null-checks and fallback logic to maintain stability across varying interface configurations.