CVE-2024-26666 is a high-severity vulnerability identified in the Linux kernel's mac80211 wireless subsystem, specifically related to the TDLS (Tunneled Direct Link Setup) fast transmit (fast-xmit) functionality. The vulnerability arises from improper use of Read-Copy-Update (RCU) synchronization mechanisms when looking up the TDLS link. RCU is a synchronization technique used in the Linux kernel to allow readers to access data concurrently with writers, without locking overhead. However, in this case, the code looks up the TDLS link under the assumption of RCU protection, but this protection is not guaranteed, leading to a potential use-after-free or race condition scenario. This flaw can be exploited by a local attacker with low privileges (PR:L) and no user interaction (UI:N) to cause significant impact on confidentiality, integrity, and availability of the system. The CVSS v3.1 base score is 7.8, indicating a high severity vulnerability. The attack vector is local (AV:L), meaning the attacker must have local access to the system, but the attack complexity is low (AC:L), and privileges required are low (PR:L). Exploitation could allow an attacker to execute arbitrary code or cause denial of service by corrupting kernel memory or crashing the system. The vulnerability affects Linux kernel versions containing the vulnerable mac80211 implementation prior to the patch. No known exploits are currently reported in the wild, but the presence of a patch indicates that Linux maintainers have addressed the issue. This vulnerability is particularly relevant for systems using Wi-Fi with TDLS enabled, which is common in many modern Linux-based devices and servers that rely on wireless networking.

For European organizations, this vulnerability poses a significant risk especially to those relying on Linux-based infrastructure with wireless connectivity, including enterprise servers, network appliances, and IoT devices. Exploitation could lead to unauthorized privilege escalation, kernel-level code execution, or denial of service, potentially disrupting critical services and exposing sensitive data. Industries such as telecommunications, finance, healthcare, and government agencies that use Linux extensively and depend on wireless networking are particularly at risk. The local attack vector means that attackers would need some form of local access, which could be achieved through compromised user accounts, insider threats, or physical access. Given the high confidentiality, integrity, and availability impacts, successful exploitation could lead to data breaches, service outages, and loss of trust. Moreover, wireless networks are often used in office environments and remote work setups, increasing the attack surface. The lack of known exploits in the wild currently provides a window for proactive patching and mitigation before widespread exploitation occurs.

European organizations should prioritize applying the official Linux kernel patches that fix the RCU use in the mac80211 TDLS fast-xmit code. Since this vulnerability requires local access, organizations should also strengthen endpoint security by enforcing strict user access controls, limiting local user privileges, and monitoring for suspicious local activity. Disabling TDLS functionality on wireless interfaces where it is not required can reduce the attack surface. Network segmentation should be employed to isolate critical systems from less trusted wireless networks. Regularly updating Linux distributions and kernel versions to incorporate security patches is essential. Additionally, organizations should audit their wireless configurations to ensure that only necessary features are enabled and that wireless drivers are up to date. Employing host-based intrusion detection systems (HIDS) to detect anomalous kernel behavior and memory corruption attempts can provide early warning. Finally, educating users about the risks of local compromise and enforcing strong physical security controls will help mitigate the risk of local exploitation.