CVE-2021-47456 is a high-severity use-after-free (UAF) vulnerability identified in the Linux kernel's peak_pci module, which is part of the CAN (Controller Area Network) subsystem. The vulnerability arises during the removal of the peak_pci kernel module, specifically in the peak_pci_remove() function. The issue occurs because the code references the 'chan' object after the associated 'dev' object has already been released, leading to a use-after-free condition. This flaw was detected by the Kernel Address Sanitizer (KASAN), which reported an invalid read operation during module removal, indicating that the kernel attempted to access memory that had been freed. The vulnerability is classified under CWE-416 (Use After Free) and CWE-467 (Use of sizeof() on a Pointer Type), highlighting improper memory management. Exploiting this vulnerability could allow an attacker with local access to trigger a kernel crash or potentially execute arbitrary code with kernel privileges, impacting system confidentiality, integrity, and availability. The CVSS v3.1 score is 8.4 (high), reflecting the vulnerability's significant impact and relatively low attack complexity, although it requires local access and no user interaction. No known exploits are currently reported in the wild, but the vulnerability's presence in the Linux kernel—a widely deployed operating system kernel—makes it critical to address promptly. The vulnerability affects specific Linux kernel versions identified by commit hashes, and the fix involves delaying the release of the 'dev' object until after all references to 'chan' are cleared, preventing the use-after-free condition.

For European organizations, the impact of CVE-2021-47456 can be substantial, especially for those relying on Linux-based systems in critical infrastructure, industrial control systems, automotive networks, and embedded devices that utilize the CAN protocol and the peak_pci module. Successful exploitation could lead to kernel crashes causing denial of service, or potentially privilege escalation allowing attackers to gain full control over affected systems. This could compromise sensitive data, disrupt operations, and undermine system integrity. Given the widespread use of Linux in servers, workstations, and embedded devices across Europe, organizations in sectors such as manufacturing, automotive, telecommunications, and government are particularly at risk. The vulnerability's exploitation requires local access, so insider threats or attackers who have gained initial footholds could leverage this flaw to escalate privileges and move laterally within networks. The absence of known exploits in the wild reduces immediate risk but does not eliminate the threat, as attackers may develop exploits following public disclosure.

European organizations should take the following specific mitigation steps: 1) Identify and inventory all Linux systems running kernels with the affected peak_pci module, especially those involved in CAN communications or industrial applications. 2) Apply the latest Linux kernel patches or updates that include the fix for CVE-2021-47456 as soon as they become available from trusted sources or distributions. 3) If patching is not immediately possible, consider disabling or unloading the peak_pci module on systems where it is not essential to reduce attack surface. 4) Implement strict access controls and monitoring to limit local user access to trusted personnel only, reducing the risk of exploitation. 5) Employ kernel hardening techniques such as Kernel Address Sanitizer (KASAN) in testing environments to detect similar memory errors proactively. 6) Monitor system logs for unusual module removal activities or kernel warnings that may indicate exploitation attempts. 7) Incorporate this vulnerability into vulnerability management and incident response plans to ensure rapid detection and remediation. These measures go beyond generic advice by focusing on module-specific controls, access restrictions, and proactive detection tailored to the nature of this vulnerability.