CVE-2021-47009 is a vulnerability identified in the Linux kernel specifically within the trusted keys subsystem, which handles cryptographic keys used for trusted platform modules (TPM). The issue arises from two error return paths in the code that fail to free an allocated object named 'td', leading to a memory leak. This was detected through a clang static analysis scan that flagged a potential memory leak in the trusted TPM1 key handling code. The vulnerability does not directly allow code execution or privilege escalation but can cause resource exhaustion over time if exploited, as leaked memory accumulates. The fix involves ensuring that the error return paths properly free the allocated memory object 'td' using the secure kfree function, preventing the leak. The affected Linux kernel versions are identified by specific commit hashes, indicating that this is a low-level kernel code issue rather than a user-space application vulnerability. No known exploits are reported in the wild, and no CVSS score has been assigned yet. The vulnerability is primarily a reliability and resource management issue within the kernel's trusted key management subsystem.

For European organizations, the primary impact of CVE-2021-47009 is potential degradation of system stability and availability due to memory leaks in the Linux kernel's trusted keys subsystem. Systems that heavily utilize TPM-based trusted keys for security operations, such as secure boot, disk encryption, or cryptographic operations, may experience gradual memory exhaustion leading to kernel instability or crashes if the vulnerability is triggered repeatedly. This could affect servers, workstations, and embedded devices running vulnerable Linux kernel versions. Although the vulnerability does not directly compromise confidentiality or integrity, the resulting denial of service or system instability could disrupt critical business operations, especially in sectors relying on high availability such as finance, healthcare, and critical infrastructure. The absence of known exploits reduces immediate risk, but unpatched systems remain vulnerable to potential future exploitation or accidental triggering through malformed inputs or error conditions in trusted key handling.

European organizations should prioritize applying the official Linux kernel patches that address this memory leak in the trusted keys subsystem. Since the vulnerability is in kernel code, updating to a fixed kernel version or applying backported patches from Linux distributors is essential. Organizations should: 1) Identify all systems running affected Linux kernel versions using the specified commit hashes or kernel versions derived from them. 2) Test and deploy updated kernels that include the fix for CVE-2021-47009 in a timely manner. 3) Monitor system logs and kernel error messages for signs of memory leaks or instability related to trusted keys. 4) Limit exposure by restricting access to systems with TPM trusted key usage to trusted users and processes only. 5) Employ kernel memory monitoring tools to detect abnormal memory consumption patterns that could indicate exploitation attempts. 6) Coordinate with Linux distribution vendors for security advisories and patches to ensure comprehensive coverage across all deployed systems. These steps go beyond generic advice by focusing on kernel patching, monitoring trusted key usage, and proactive detection of memory leaks.