CVE-2026-90380 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: mt76: mt792x: fix use-after-free in mt76_rx_poll_complete
A use-after-free issue occurs in mt76_rx_poll_complete due to a race condition. The STA has already been removed, but the rx_status still had a pointer to the wcid in the STA.
Set the links' wcid pointers to be NULL for a MLD in mt7925_sta_pre_rcu_remove()
BUG: KASAN: invalid-access in mt76_rx_poll_complete+0x280/0x470 Call trace: dump_backtrace+0xec/0x128 show_stack+0x18/0x28 dump_stack_lvl+0x40/0xc8 print_report+0x1b8/0x710 kasan_report+0xe0/0x144 do_bad_area+0x120/0x260 do_tag_check_fault+0x20/0x34 do_mem_abort+0x54/0xa8 el1_abort+0x3c/0x5c el1h_64_sync_handler+0x40/0xcc el1h_64_sync+0x7c/0x80 mt76_rx_poll_complete+0x280/0x470 mt76_dma_rx_poll+0x114/0x51c mt792x_poll_rx+0x60/0xf8 napi_threaded_poll_loop+0xe0/0x450 napi_threaded_poll+0x80/0x9c kthread+0x11c/0x158 ret_from_fork+0x10/0x20
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Analysis
by VulDB Data Team • 09/17/2026
The Linux kernel driver for MediaTek MT792X wireless network interfaces contains a critical memory safety vulnerability identified as a use-after-free condition within the mt76_rx_poll_complete function. This flaw arises from a race condition involving the management of Station (STA) contexts and their associated Wireless Context IDs (WCID). In the context of Wi-Fi drivers, WCIDs serve as identifiers for specific client connections, allowing the driver to track state information such as encryption keys, QoS settings, and link parameters. The vulnerability manifests when an STA is removed from the system while there are still pending receive operations or polling loops that reference the now-invalid memory associated with that STA's context.
The root cause of this issue lies in the timing of pointer invalidation during the removal process. When a station disconnects or is explicitly removed, the kernel invokes mt7925_sta_pre_rcu_remove to begin cleaning up resources. However, prior to this fix, the pointers within Multi-Link Device (MLD) links that reference the WCID were not immediately set to NULL upon initiation of the removal process. Consequently, if a receive poll cycle was actively processing packets for that STA at the moment of removal, it would continue to access memory locations associated with the freed or invalidating WCID structure. This creates a window where valid-looking pointers exist in active execution paths but point to deallocated kernel memory.
The operational impact of this vulnerability is severe, as evidenced by Kernel Address Sanitizer (KASAN) reports indicating an invalid-access error within mt76_rx_poll_complete. Such use-after-free conditions can lead to unpredictable system behavior, including kernel panics and denial-of-service scenarios where the wireless subsystem crashes due to illegal memory access. In more sophisticated attack vectors, if an attacker can influence the timing of STA removal relative to packet processing, they might exploit this race condition to achieve arbitrary code execution by overwriting freed memory with controlled data structures that are subsequently dereferenced. This represents a significant stability and security risk for systems relying on MT792X hardware for network connectivity.
To mitigate this vulnerability, the fix ensures that all link-specific WCID pointers within an MLD context are explicitly set to NULL during the mt7925_sta_pre_rcu_remove phase of STA teardown. This immediate nullification prevents subsequent polling loops from accessing stale references, effectively closing the race window between resource deallocation and active memory access. From a security classification perspective, this flaw aligns with CWE-416: Use After Free, which describes errors resulting from referencing memory after it has been freed. Furthermore, in terms of adversarial tactics, exploiting such kernel-level use-after-free conditions is consistent with ATT&CK technique T1055: Process Injection or more broadly T1218: Signed Binary Proxy Execution if the goal is to escalate privileges within the operating system environment by compromising the integrity of the kernel memory space. System administrators should apply the corresponding kernel patch updates to ensure that the driver correctly handles reference counting and pointer invalidation during station disassociation events.