CVE-2025-2923 is a heap-based buffer overflow vulnerability identified in the HDF5 library, specifically affecting versions 1.14.0 through 1.14.6. The flaw resides in the function H5F_addr_encode_len within the source file src/H5Fint.c. The vulnerability arises from improper handling and manipulation of the argument 'pp', which leads to a heap-based buffer overflow condition. This type of vulnerability can allow an attacker to overwrite adjacent memory on the heap, potentially leading to arbitrary code execution, application crashes, or data corruption. However, exploitation requires local access with at least low privileges (PR:L), and no user interaction is needed. The vulnerability does not affect confidentiality, integrity, or availability directly in a network context since it requires local access and privileges, and no authentication bypass or remote exploitation vector is present. The CVSS 4.0 base score is 4.8, indicating a medium severity level. The exploit has been publicly disclosed, increasing the risk of exploitation, although no known exploits in the wild have been reported to date. The vulnerability is classified as problematic, meaning it is significant but not critical. The HDF5 library is widely used for managing and storing large scientific data sets, commonly in research, engineering, and data-intensive applications. This vulnerability could impact any software or systems that embed or rely on these affected HDF5 versions for data handling.

For European organizations, the impact of CVE-2025-2923 depends largely on their use of the HDF5 library within local applications or systems. Organizations involved in scientific research, engineering, data analytics, and industries such as aerospace, automotive, pharmaceuticals, and academia are more likely to use HDF5. A successful exploitation could lead to local privilege escalation or arbitrary code execution, potentially allowing attackers to manipulate or corrupt critical data sets or disrupt data processing workflows. Although remote exploitation is not feasible, insider threats or compromised local accounts could leverage this vulnerability to escalate privileges or cause denial of service. The impact on confidentiality is limited due to the local attack vector, but integrity and availability of data could be compromised. European research institutions and companies handling large-scale scientific data may face operational disruptions or data integrity issues if this vulnerability is exploited.

To mitigate CVE-2025-2923, European organizations should prioritize upgrading to a patched version of the HDF5 library once available, as no patch links are currently provided but are expected soon given the public disclosure. Until patches are released, organizations should restrict local access to systems running vulnerable HDF5 versions, enforce strict user privilege management, and monitor for unusual local activity that could indicate exploitation attempts. Application developers using HDF5 should audit their code to ensure safe handling of HDF5 data and consider implementing additional input validation around HDF5 API calls. Employing runtime protections such as heap overflow detection tools, AddressSanitizer, or similar memory safety mechanisms can help detect exploitation attempts during development and testing. Additionally, organizations should maintain robust endpoint security controls and local intrusion detection to identify and respond to potential exploitation attempts promptly.