CVE-2025-6120 is a heap-based buffer overflow vulnerability identified in the Open Asset Import Library (Assimp) versions 5.4.0 through 5.4.3. The vulnerability resides specifically in the function read_meshes within the source file assimp/code/AssetLib/MDL/HalfLife/HL1MDLLoader.cpp. This function is responsible for processing mesh data from 3D model files, particularly those related to the Half-Life MDL format. The flaw arises due to improper handling of input data leading to a heap buffer overflow condition. An attacker with local access and low-level privileges can exploit this vulnerability without requiring user interaction, potentially causing memory corruption. Although the CVSS score is 4.8 (medium severity), the vulnerability can impact confidentiality, integrity, and availability to a limited extent due to the local attack vector and requirement for low privileges. The exploit has been publicly disclosed, increasing the risk of exploitation, but no known active exploits in the wild have been reported to date. The Assimp project has acknowledged multiple fuzzer-discovered bugs and plans to address them collectively in future updates. Assimp is widely used in applications that import and process 3D assets, including game engines, modeling tools, and visualization software, making this vulnerability relevant for software relying on these components for 3D model handling.

For European organizations, the impact of this vulnerability depends largely on the use of Assimp within their software stack. Organizations involved in game development, 3D modeling, CAD, simulation, and visualization that incorporate Assimp versions 5.4.0 to 5.4.3 are at risk. Exploitation could lead to local privilege escalation or denial of service through application crashes or memory corruption. While remote exploitation is not possible without local access, insider threats or compromised user accounts could leverage this flaw to escalate privileges or disrupt critical 3D asset processing workflows. This could affect software development firms, digital media companies, and industries relying on 3D visualization such as automotive, aerospace, and architecture. The medium severity rating reflects limited attack scope but non-negligible risk to data integrity and system stability. Given the public disclosure, European organizations should prioritize assessment and remediation to prevent potential exploitation, especially in environments where Assimp is integrated into critical or sensitive applications.

1. Immediate mitigation involves upgrading Assimp to a version beyond 5.4.3 once patches addressing this vulnerability are released. Since no patch links are currently available, organizations should monitor the Assimp project repository and security advisories for updates. 2. In the interim, restrict local access to systems running vulnerable Assimp versions to trusted users only, minimizing the risk of local exploitation. 3. Employ application-level sandboxing or containerization to limit the impact of potential memory corruption caused by exploitation. 4. Conduct thorough code audits and fuzz testing on any custom software integrating Assimp to identify and mitigate similar memory handling issues. 5. Implement strict input validation and sanitization on 3D model files before processing to reduce malformed input risks. 6. Monitor system logs and application behavior for signs of crashes or anomalous activity related to 3D asset processing. 7. Educate developers and security teams about the risks associated with third-party libraries like Assimp and incorporate dependency vulnerability scanning into the software development lifecycle.