CVE-2025-21828 is a vulnerability identified in the Linux kernel's mac80211 wireless subsystem, specifically related to the handling of station (STA) states in Wi-Fi networks. The issue arises when a station's state is pre-moved to AUTHORIZED, such as in Independent Basic Service Set (IBSS) scenarios, but the insertion of the station into the driver fails. In this failure case, the station object is freed without the driver ever being aware of its existence. Subsequently, when the kernel attempts to flush this non-uploaded station, it encounters an unexpected condition that may lead to a system crash. This occurs because the flushing operation assumes the station was registered with the driver, but since it was not, the operation accesses invalid memory or state, causing instability. The vulnerability is rooted in improper state management and lack of verification before flushing station entries. The fix involves adding checks to confirm whether the station was uploaded to the driver before attempting to flush it, thereby preventing the crash scenario. This vulnerability affects Linux kernel versions identified by the commit hash d00800a289c9349bb659a698cbd7bc04521dc927 and potentially other versions with similar mac80211 implementations. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, this vulnerability could lead to denial of service (DoS) conditions on systems running vulnerable Linux kernels with affected mac80211 wireless drivers. Since the flaw can cause kernel crashes when handling Wi-Fi station states, critical infrastructure relying on stable wireless connectivity—such as enterprise networks, industrial control systems, and public service Wi-Fi—could experience outages or degraded service. This is particularly relevant for organizations using Linux-based routers, access points, or embedded devices in wireless networks. The impact on confidentiality and integrity is limited, as the vulnerability primarily causes availability issues through crashes rather than unauthorized access or data manipulation. However, repeated crashes could be exploited by attackers to disrupt services or cause operational downtime. Given the widespread use of Linux in servers, network devices, and IoT in Europe, the potential for disruption exists but requires specific conditions related to wireless station management and IBSS scenarios, which may limit the attack surface. Nonetheless, organizations with critical wireless infrastructure should prioritize patching to maintain network stability.

To mitigate this vulnerability, European organizations should: 1) Identify and inventory Linux systems running kernel versions with the affected mac80211 implementation, especially those managing wireless networks or acting as access points. 2) Apply the official Linux kernel patches or updates that include the fix for CVE-2025-21828 as soon as they are released. 3) For embedded or specialized devices, coordinate with vendors to obtain firmware updates incorporating the patch. 4) Monitor system logs for unusual wireless subsystem errors or kernel crashes that could indicate attempts to trigger this vulnerability. 5) Limit exposure by restricting access to wireless management interfaces and ensuring that only trusted devices participate in IBSS or similar wireless modes. 6) Implement network segmentation to isolate critical wireless infrastructure from less secure network segments to reduce the risk of exploitation. 7) Maintain up-to-date backups and recovery procedures to quickly restore services in case of disruption caused by this or related vulnerabilities.