CVE-2021-47568 is a vulnerability identified in the Linux kernel specifically related to the ksmbd module, which is responsible for providing SMB (Server Message Block) server functionality within the kernel. The vulnerability concerns a memory leak in the function get_file_stream_info(). A memory leak occurs when allocated memory is not properly released after use, which can lead to increased memory consumption over time. In this case, the leak happens when the get_file_stream_info() function is called, potentially causing the kernel to consume more memory than necessary. While a memory leak itself does not directly allow code execution or privilege escalation, it can degrade system performance and stability, potentially leading to denial of service (DoS) conditions if the system runs out of memory. The vulnerability has been addressed by fixing the memory leak in the affected function. The affected versions are identified by specific commit hashes, indicating that this is a source-level issue in the Linux kernel codebase. There are no known exploits in the wild at this time, and no CVSS score has been assigned. The vulnerability does not require authentication or user interaction to manifest, as it is within the kernel SMB server component, which may be exposed on systems offering SMB services.

For European organizations, the impact of this vulnerability depends largely on the deployment of Linux systems running the vulnerable kernel versions with the ksmbd SMB server enabled. Organizations using Linux servers as file servers or SMB shares could experience gradual degradation of system performance due to memory leaks, potentially leading to service interruptions or denial of service if memory exhaustion occurs. This could affect critical infrastructure, enterprise file sharing, and internal collaboration services. While the vulnerability does not directly lead to remote code execution or data breaches, the resulting instability could disrupt business operations, especially in environments with high SMB traffic. Additionally, memory leaks can sometimes be leveraged as part of more complex attack chains, although no such exploits are currently known. European organizations with large-scale Linux deployments, particularly those using native Linux SMB implementations rather than Samba or other user-space SMB servers, should be aware of this risk.

To mitigate this vulnerability, European organizations should: 1) Apply the official Linux kernel patches that fix the memory leak in the ksmbd get_file_stream_info() function as soon as they are available and tested. 2) Monitor memory usage on Linux servers running SMB services to detect abnormal increases that could indicate exploitation or the presence of the leak. 3) Consider temporarily disabling the ksmbd SMB server module if it is not essential, or switch to alternative SMB implementations such as Samba until patches are applied. 4) Implement resource limits and monitoring to prevent memory exhaustion from impacting critical services. 5) Maintain up-to-date kernel versions and subscribe to Linux kernel security advisories to promptly respond to new vulnerabilities. 6) Conduct regular security audits of SMB services and network exposure to reduce attack surface.