CVE-2020-35632 is a security vulnerability identified in the CGAL Project's libcgal library version 5.1.1, specifically within the Nef polygon-parsing functionality. The vulnerability arises due to improper validation of array indices (CWE-129) in the code handling polygon data structures, particularly in the file SNC_io_parser.h within the Nef_S2/SNC_io_parser<EW>::read_sface() function. This flaw allows an attacker to craft a malformed input file that triggers an out-of-bounds (OOB) read and type confusion. The OOB read occurs when the parser attempts to access elements outside the bounds of an array, leading to undefined behavior and potential memory corruption. The type confusion can cause the program to misinterpret data types, potentially enabling arbitrary code execution. Exploiting this vulnerability requires an attacker to supply maliciously crafted polygon files to an application that uses libcgal 5.1.1 for polygon parsing. Since the vulnerability is triggered during file parsing, it may be exploited remotely if the application processes untrusted input files. No authentication or user interaction is explicitly required beyond supplying the malicious input. Although no known exploits are reported in the wild, the vulnerability poses a risk of remote code execution, which can compromise confidentiality, integrity, and availability of affected systems. The lack of a patch link indicates that remediation may require updating to a later, fixed version of libcgal or applying vendor-provided patches once available. The vulnerability is categorized as medium severity, reflecting the complexity of exploitation and the specific conditions needed to trigger it.

For European organizations, the impact of CVE-2020-35632 depends largely on the extent to which libcgal 5.1.1 is integrated into their software stacks, particularly in industries relying on computational geometry, CAD, GIS, or scientific computing. Successful exploitation could lead to arbitrary code execution, enabling attackers to execute malicious code with the privileges of the vulnerable application. This could result in data breaches, system compromise, or disruption of critical services. Organizations processing untrusted polygon data files—such as engineering firms, research institutions, or geospatial data providers—are at higher risk. The vulnerability could be leveraged to infiltrate internal networks, especially if the vulnerable software is exposed to external inputs or used in automated processing pipelines. Given the potential for remote exploitation without authentication, the threat could facilitate lateral movement or persistence within networks. However, the medium severity and absence of known exploits suggest that the immediate risk is moderate, but organizations should not disregard the vulnerability due to its potential for serious impact if exploited.

1. Update libcgal to the latest version where this vulnerability is addressed. Monitor the CGAL Project's official channels for patches or new releases that fix CVE-2020-35632. 2. Implement strict input validation and sanitization on all polygon data files before processing, including rejecting malformed or suspicious files. 3. Employ sandboxing or containerization for applications using libcgal to limit the impact of potential exploitation. 4. Restrict access to services or applications that parse polygon files to trusted users and networks, minimizing exposure to untrusted inputs. 5. Conduct code audits and static analysis on custom software integrating libcgal to detect unsafe array indexing or parsing logic. 6. Monitor logs and network traffic for anomalous activity that could indicate exploitation attempts involving polygon file processing. 7. Where feasible, disable or limit the use of the vulnerable Nef polygon parsing functionality if it is not essential to operations. 8. Educate developers and system administrators about this vulnerability to ensure timely patching and secure coding practices.