CVE-2022-42721 is a vulnerability identified in the mac80211 wireless stack of the Linux kernel versions 5.1 through 5.19.x prior to 5.19.16. The issue stems from a list management bug in the Basic Service Set (BSS) handling code. Specifically, the vulnerability involves improper handling of linked lists when processing WLAN frames, which can be manipulated by a local attacker who has the capability to inject WLAN frames. By exploiting this flaw, an attacker could corrupt the linked list structure used internally by the mac80211 subsystem. This corruption could lead to undefined behavior, including potential arbitrary code execution within the kernel context. The vulnerability requires local privileges with the ability to inject WLAN frames, which typically implies control over a wireless interface or the ability to spoof or inject frames in the local wireless environment. The CVSS v3.1 base score is 5.5 (medium severity), with vector AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating that the attack vector is local, requires low attack complexity, low privileges, no user interaction, unchanged scope, no confidentiality or integrity impact, but high impact on availability. The CWE classification is CWE-835 (Loop with Unreachable Exit Condition, which can lead to resource exhaustion or corruption). No known exploits in the wild have been reported, and no official patches are linked in the provided data, though kernel version 5.19.16 and later presumably address the issue. This vulnerability is significant because it affects the Linux kernel's wireless networking stack, a critical component for many devices and systems relying on Wi-Fi connectivity. Exploitation could lead to denial of service or potentially escalate to code execution, compromising system stability and security.

For European organizations, this vulnerability poses a risk primarily to systems running vulnerable Linux kernel versions with wireless capabilities. Many enterprises, research institutions, and government agencies in Europe use Linux-based systems, including servers, desktops, and embedded devices. The ability to inject WLAN frames locally is a limiting factor; however, in environments with shared wireless networks or where attackers can gain proximity, this could be exploited to disrupt availability or potentially execute code with kernel privileges. This could lead to denial of service conditions, impacting critical infrastructure, industrial control systems, or enterprise IT operations. Additionally, compromised systems could be leveraged for lateral movement or further attacks within the network. Given the widespread use of Linux in European telecommunications, public sector, and industrial environments, the impact could be significant if not mitigated. The lack of confidentiality and integrity impact reduces the risk of data breaches directly from this vulnerability, but availability disruptions and potential kernel-level compromise remain serious concerns.

1. Upgrade Linux kernels to version 5.19.16 or later, where the vulnerability has been addressed. 2. For systems that cannot be immediately updated, restrict wireless frame injection capabilities by enforcing strict wireless network access controls and monitoring for anomalous WLAN frame activity. 3. Employ wireless intrusion detection/prevention systems (WIDS/WIPS) to detect and block unauthorized frame injection attempts. 4. Limit physical and logical access to wireless interfaces, especially in sensitive environments, to reduce the risk of local attackers gaining the ability to inject frames. 5. Regularly audit and monitor kernel logs and system behavior for signs of exploitation or instability related to wireless networking. 6. For embedded or specialized devices, coordinate with vendors for firmware updates or patches addressing this vulnerability. 7. Implement network segmentation to isolate vulnerable Linux systems from critical assets, minimizing potential lateral movement if exploitation occurs.