CVE-2025-6817 is a resource consumption vulnerability identified in the HDF5 library version 1.14.6, specifically within the function H5C__load_entry located in the source file /src/H5Centry.c. HDF5 is a widely used data model, library, and file format for storing and managing large amounts of data, commonly employed in scientific computing, engineering, and data analytics. The vulnerability arises from improper handling of resource allocation during the loading of cache entries, which can be manipulated by a local attacker to cause excessive resource consumption, potentially leading to denial of service (DoS) conditions. The attack vector requires local access with low privileges (PR:L), no user interaction, and no elevated authentication beyond local access. The CVSS v4.0 score is 4.8 (medium severity), reflecting limited impact on confidentiality, integrity, and availability, but with a potential to degrade system performance or availability due to resource exhaustion. The vulnerability does not require network access or user interaction, but exploitation is limited to local users with some privileges. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability disclosure is recent (June 28, 2025), and the exploit code has been publicly disclosed, increasing the risk of exploitation in environments where vulnerable HDF5 versions are deployed.

For European organizations, the impact of CVE-2025-6817 primarily concerns systems that utilize HDF5 1.14.6 for data storage and processing, particularly in research institutions, scientific computing centers, engineering firms, and industries relying on large-scale data analytics. Resource consumption vulnerabilities can lead to denial of service by exhausting memory or CPU resources, potentially disrupting critical data processing workflows. Although the attack requires local access, insider threats or compromised local accounts could exploit this vulnerability to degrade system availability. In sectors such as healthcare, energy, and manufacturing, where HDF5 is often used for managing complex datasets, such disruptions could delay operations or analysis, impacting decision-making and service delivery. The medium severity rating suggests that while the vulnerability is not critical, it still poses a tangible risk to system stability and availability, which European organizations should address promptly to maintain operational continuity and data integrity.

To mitigate CVE-2025-6817, European organizations should: 1) Immediately audit their environments to identify deployments of HDF5 version 1.14.6 and assess exposure to local users with access to vulnerable systems. 2) Restrict local access privileges to trusted users only, implementing strict access controls and monitoring for unusual resource usage patterns that could indicate exploitation attempts. 3) Apply any available patches or updates from the HDF5 maintainers as soon as they are released; if no official patch exists yet, consider upgrading to a later, unaffected version of HDF5. 4) Employ system-level resource limits (e.g., cgroups on Linux) to constrain the maximum resources any single process or user can consume, thereby limiting the impact of resource exhaustion attacks. 5) Enhance logging and alerting mechanisms to detect abnormal resource consumption or process behavior related to HDF5 operations. 6) Educate local users and administrators about the risk of this vulnerability and the importance of maintaining strict local access policies. These measures go beyond generic advice by focusing on local access control, resource management, and proactive monitoring tailored to the nature of this vulnerability.