CVE-2024-26961 is a use-after-free vulnerability in the Linux kernel's mac802154 subsystem, which handles IEEE 802.15.4 wireless communication, commonly used in low-power wireless personal area networks (WPANs). The flaw arises in the mac802154_llsec_key_del() function responsible for deleting link-layer security (LLSEC) keys. This function improperly frees key resources without adhering to Read-Copy-Update (RCU) synchronization rules, specifically failing to wait for the RCU grace period before releasing memory. As a result, concurrent operations such as llsec_lookup_key(), which traverse the list of keys, may access freed memory, leading to use-after-free conditions. This can cause kernel warnings, crashes, or potentially arbitrary code execution in kernel context if exploited. Additionally, the vulnerability includes a resource leak where ieee802154_llsec_key_entry structures are not freed properly, compounding resource management issues. The root cause is improper reference counting and delayed freeing of key entries, which the patch addresses by moving resource release to an RCU callback function (mac802154_llsec_key_del_rcu()). This ensures safe memory reclamation after all readers have finished accessing the data. The vulnerability was discovered by the Linux Verification Center and affects Linux kernel versions prior to the fix, including the 6.7.0 kernel referenced. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2024-26961 depends largely on the deployment of Linux systems utilizing the mac802154 subsystem, which is specialized for IEEE 802.15.4 wireless communications. This technology is often used in industrial IoT, smart metering, building automation, and wireless sensor networks. Organizations in sectors such as manufacturing, utilities, smart cities, and critical infrastructure that rely on Linux-based embedded devices or gateways with 802.15.4 support could be at risk. Exploitation could lead to kernel crashes causing denial of service or, in worst cases, privilege escalation and arbitrary code execution within the kernel, compromising system integrity and confidentiality. Given the kernel-level nature of the flaw, successful exploitation could allow attackers to bypass security controls and gain persistent control over affected devices. This poses risks to operational continuity and data security, especially in environments where these wireless protocols are integral to system operations. However, the specialized nature of the affected subsystem limits the scope compared to more general Linux kernel vulnerabilities. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time.

European organizations should prioritize patching Linux kernels to versions that include the fix for CVE-2024-26961. Specifically, updating to kernel versions released after the fix (post-6.7.0 or corresponding stable releases) is critical. For embedded or specialized devices where kernel upgrades are challenging, organizations should work with vendors to obtain patched firmware or kernel updates. Additionally, organizations should audit their environments to identify systems using IEEE 802.15.4 mac802154 drivers and assess exposure. Network segmentation and strict access controls should be enforced around devices using this technology to limit potential attack vectors. Monitoring kernel logs for refcount warnings or unusual crashes related to mac802154 can help detect attempted exploitation. Employing runtime security tools capable of detecting use-after-free or memory corruption in kernel space may provide early warning. Finally, organizations should review and harden wireless network configurations to reduce unauthorized access to WPAN devices, including strong authentication and encryption where supported.