CVE-2025-47711 is an off-by-one error vulnerability identified in the nbdkit server component, which is part of Red Hat Enterprise Linux 10 distributions (versions 1.11.10, 1.40.0, and 1.42.0). The nbdkit server acts as a network block device server that allows plugins to provide data blocks to clients. The vulnerability arises when the server handles plugin responses about the status of data blocks. Specifically, if a client issues a request for a very large data range, and the plugin responds with a single data block that is even larger than the requested range, the server's internal logic fails to correctly handle this scenario due to an off-by-one error. This leads to a critical internal error within the nbdkit server, causing it to crash or become unresponsive, resulting in a denial-of-service (DoS) condition. The vulnerability requires an attacker to have network access and low complexity privileges (PR:L), but no user interaction is needed. The flaw does not affect confidentiality or integrity but impacts availability by disrupting the service. No patches or exploit code are currently publicly available, and no known exploits have been reported in the wild. The medium CVSS score of 4.3 reflects the moderate impact and limited exploitability. This vulnerability is particularly relevant for environments where nbdkit is used to serve large data blocks over the network, such as in virtualization or storage infrastructure.

For European organizations, the primary impact of CVE-2025-47711 is the potential disruption of services relying on the nbdkit server, which is commonly used in virtualization and storage solutions within enterprise Linux environments. A successful exploitation can cause denial-of-service, leading to downtime of critical infrastructure components, impacting business continuity and operational efficiency. While the vulnerability does not compromise data confidentiality or integrity, the availability impact can affect cloud service providers, data centers, and enterprises using Red Hat Enterprise Linux 10 with nbdkit for network block device services. This can be particularly critical for sectors such as finance, healthcare, telecommunications, and government services where high availability is essential. Additionally, the requirement for low-level privileges means insider threats or compromised accounts could exploit this vulnerability to disrupt services. The absence of known exploits reduces immediate risk but does not eliminate the need for proactive mitigation.

To mitigate CVE-2025-47711, European organizations should: 1) Monitor Red Hat advisories closely and apply patches or updates for nbdkit as soon as they become available. 2) Restrict network access to nbdkit servers to trusted clients only, using network segmentation and firewall rules to limit exposure. 3) Implement strict access controls and privilege management to minimize the risk of low-privilege accounts being used to exploit the vulnerability. 4) Monitor nbdkit server logs and system behavior for signs of crashes or abnormal terminations that could indicate exploitation attempts. 5) Consider deploying runtime protections or application-level monitoring to detect anomalous plugin responses or unusually large data block requests. 6) In environments where patching is delayed, consider disabling or limiting the use of nbdkit plugins that handle large data ranges or implementing rate limiting on client requests to reduce the risk of triggering the vulnerability. 7) Conduct regular vulnerability assessments and penetration testing focusing on network block device services to identify potential exploitation vectors.