CVE-2021-47401 is a vulnerability identified in the Linux kernel, specifically related to the ipack driver and its ipoctal component. The issue arises from improper handling of the tty driver name, which is used after the driver registration process. The vulnerability stems from the fact that the tty driver name was allocated on the stack, leading to a potential stack information leak. This can inadvertently expose sensitive kernel stack data to user space, which could be exploited by an attacker to gain insights into kernel memory layout or cause kernel instability (e.g., triggering an oops). The root cause is that drivers improperly encode topology information within the tty device name, a practice that was introduced through staging drivers without adequate review. While the fix addresses the immediate security hole by ensuring the tty driver name is not allocated on the stack, a more comprehensive fix involving the Application Binary Interface (ABI) is noted as a separate concern. No known exploits are currently reported in the wild for this vulnerability, and no CVSS score has been assigned yet. The vulnerability affects specific Linux kernel versions identified by commit hashes, indicating it is present in certain recent or development builds. Overall, this vulnerability represents a kernel information leak through improper memory handling in device driver code, which could be leveraged for further attacks if combined with other vulnerabilities or local access.

For European organizations, the impact of CVE-2021-47401 depends largely on their use of affected Linux kernel versions and the deployment of ipack/ipoctal drivers. Since Linux is widely used across European enterprises, especially in servers, cloud infrastructure, and embedded systems, this vulnerability could potentially expose sensitive kernel memory information to local users or processes. This information leak could facilitate privilege escalation or kernel exploitation in multi-tenant environments such as cloud service providers or shared hosting platforms common in Europe. Although no remote exploitation vector is indicated, organizations with internal threat actors or compromised user accounts could see increased risk. The vulnerability could also impact embedded Linux devices used in industrial control systems, telecommunications, or IoT devices prevalent in European critical infrastructure. The lack of known exploits reduces immediate risk, but the presence of this vulnerability in kernel staging drivers suggests that less mature or custom Linux builds might be more vulnerable. Overall, the impact is primarily on confidentiality and system stability, with potential downstream effects on integrity and availability if exploited in combination with other vulnerabilities.

European organizations should prioritize updating their Linux kernels to versions where this vulnerability is patched. Since the issue relates to kernel driver code, applying official kernel updates from trusted Linux distributions (e.g., Debian, Ubuntu, Red Hat, SUSE) is the most effective mitigation. For environments using custom or embedded Linux builds, developers should review and patch the ipack/ipoctal driver code to ensure the tty driver name is not allocated on the stack. Additionally, organizations should enforce strict access controls to limit local user privileges, reducing the risk of exploitation by unprivileged users. Employing kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and restricting access to /dev/tty devices can further mitigate information leakage risks. Monitoring kernel logs for unusual oops or crashes related to tty drivers can help detect exploitation attempts. Finally, organizations should maintain an inventory of Linux kernel versions in use and apply timely security updates, especially for staging or less commonly used drivers.