CVE-2021-47455 is a vulnerability identified in the Linux kernel's Precision Time Protocol (PTP) subsystem, specifically within the ptp_clock_register() function. The flaw is a memory leak that occurs when the posix_clock_register() call fails during the registration process of a PTP clock device. The issue arises because the device name allocated by dev_set_name() is not properly freed if an error occurs, leading to unreleased memory. The root cause is that the device reference is not relinquished via put_device(), which would normally trigger cleanup routines such as kobject_cleanup() to free the allocated name and other associated resources in ptp_clock_release(). This leak was discovered through fault injection testing and is evidenced by unreferenced kernel objects related to the PTP clock device. Although the vulnerability does not directly lead to code execution or privilege escalation, the memory leak can degrade system stability over time, especially on systems heavily utilizing PTP clocks, such as those in telecommunications or industrial control environments. The affected Linux kernel versions include multiple commits identified by their hashes, indicating the vulnerability spans several recent kernel builds. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2021-47455 is primarily related to system reliability and availability. Organizations that rely on Linux-based systems for critical infrastructure—such as telecommunications providers, industrial automation, energy sector companies, and financial institutions—may experience gradual memory exhaustion or degraded performance if the PTP subsystem is heavily used and the vulnerability is unpatched. This could lead to system slowdowns, crashes, or the need for more frequent reboots, potentially disrupting time-sensitive operations. While the vulnerability does not directly compromise confidentiality or integrity, the availability impact could indirectly affect business continuity and operational efficiency. Given the widespread use of Linux in European data centers and embedded systems, unmitigated memory leaks could accumulate, especially in environments with long uptimes and high device registration activity.

To mitigate this vulnerability, European organizations should prioritize updating their Linux kernels to versions where the ptp_clock_register() memory leak has been fixed. Since the issue is related to error handling in device registration, applying the official patch or upgrading to a kernel version released after May 2024 that includes this fix is critical. Additionally, organizations should audit their systems for heavy usage of PTP clocks and monitor kernel memory usage patterns to detect abnormal leaks early. Implementing automated monitoring tools that track kernel memory consumption and device registration errors can provide early warning signs. For embedded or specialized systems where kernel upgrades are challenging, backporting the patch or applying vendor-provided fixes is recommended. Finally, system administrators should ensure that fault injection or stress testing is part of their regular security and stability assessments to uncover similar latent issues.