CVE-2026-63866 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: mt76: mt7996: Clear wcid pointer in mt7996_mac_sta_deinit_link()
Clear WCID pointer removing the sta link in mt7996_mac_sta_deinit_link routine.
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Analysis
by VulDB Data Team • 07/19/2026
The vulnerability in question involves a memory management issue within the Linux kernel's wireless subsystem, specifically affecting the MediaTek mt7996 wireless driver implementation. This flaw exists in the mt7996_mac_sta_deinit_link() function which handles the cleanup process when removing station links from wireless connections. The technical root cause stems from improper pointer handling where the WCID (Wireless Client Identifier) pointer is not properly cleared during the station deinitialization process, creating a potential dangling pointer scenario that could lead to memory corruption or undefined behavior.
The operational impact of this vulnerability extends beyond simple memory management concerns as it affects the stability and reliability of wireless network connections on systems utilizing MediaTek mt7996 chipset hardware. When a station link is removed from the wireless MAC layer, the WCID pointer should be explicitly cleared to prevent subsequent access to freed memory locations. However, the absence of this clearing operation means that references to the now-invalid WCID structure could persist in memory, potentially leading to crashes, data corruption, or exploitation opportunities for malicious actors attempting to manipulate wireless network operations.
This vulnerability aligns with CWE-415: Double Free and CWE-416: Use After Free categories from the Common Weakness Enumeration catalog, as it involves improper pointer management that could result in memory access violations. The issue demonstrates a classic memory safety problem where resource cleanup does not properly invalidate references, creating potential attack vectors for privilege escalation or denial of service conditions. From an ATT&CK framework perspective, this vulnerability could be leveraged as part of initial access or privilege escalation techniques, particularly when targeting embedded systems or network infrastructure running affected Linux kernel versions.
The mitigation strategy involves ensuring that all WCID pointers are properly cleared during the station deinitialization process within the mt7996_mac_sta_deinit_link() routine. This requires implementing explicit pointer nullification after removing station links to prevent any subsequent access attempts to freed memory structures. System administrators should prioritize applying kernel updates that include this fix, particularly on devices running wireless networking services where MediaTek mt7996 chipsets are present. The resolution addresses the core issue by guaranteeing that when station links are removed, the associated WCID pointers are properly invalidated, preventing any potential exploitation scenarios while maintaining the integrity of wireless network operations and system stability.