CVE-2020-28623 is a medium-severity vulnerability affecting version 5.1.1 of the CGAL Project's libcgal library, specifically within its Nef polygon-parsing functionality. The vulnerability arises from improper validation of array indices (CWE-129) in the SNC_io_parser<EW>::read_facet() function, which processes polygon data structures. An attacker can craft a malformed input file that triggers out-of-bounds (OOB) reads and type confusion errors during the parsing process. These memory safety issues can potentially lead to arbitrary code execution if exploited successfully. The vulnerability is rooted in the failure to correctly validate array indices before accessing elements, resulting in memory corruption. Although no known exploits are currently reported in the wild, the nature of the vulnerability—especially the possibility of code execution—makes it a significant concern for applications relying on libcgal for geometric computations and polygon parsing. The lack of a publicly available patch at the time of reporting further increases the risk for users of the affected version. The vulnerability requires an attacker to supply malicious input files to the vulnerable parsing function, which may be feasible in environments where user-supplied or external polygon data is processed without adequate sanitization or isolation.

For European organizations, the impact of this vulnerability depends largely on the extent to which libcgal 5.1.1 is integrated into their software stacks. libcgal is widely used in computational geometry, CAD software, scientific computing, and GIS applications. Organizations in sectors such as manufacturing, engineering, research institutions, and geospatial services may be particularly affected. Successful exploitation could lead to arbitrary code execution, compromising confidentiality, integrity, and availability of affected systems. This could result in unauthorized data access, manipulation of critical geometric data, or disruption of services relying on geometric computations. Given the potential for remote exploitation via crafted input files, attackers could leverage this vulnerability to gain footholds within networks, especially if parsing occurs on servers processing external data. The absence of known exploits suggests limited immediate threat, but the vulnerability's characteristics warrant proactive mitigation to prevent future attacks. Additionally, organizations involved in software development or distribution that includes libcgal should be cautious of supply chain risks.

1. Upgrade libcgal to a version where this vulnerability is patched once available; monitor CGAL Project releases and advisories closely. 2. Implement strict input validation and sanitization for all polygon or geometric data files before processing, including rejecting malformed or suspicious files. 3. Employ sandboxing or isolation techniques for processes handling external polygon data to limit potential damage from exploitation. 4. Conduct code audits and static analysis on custom software using libcgal to identify unsafe usage patterns related to array indexing. 5. Monitor logs for unusual parsing errors or crashes that could indicate exploitation attempts. 6. Where feasible, restrict access to polygon parsing functionalities to trusted users or systems to reduce exposure. 7. Consider deploying runtime protections such as Address Space Layout Randomization (ASLR), Data Execution Prevention (DEP), and Control Flow Integrity (CFI) to mitigate exploitation impact. 8. Engage with software vendors or internal development teams to ensure timely patching and secure coding practices around CGAL components.