CVE-2020-28605 is a medium-severity vulnerability affecting the CGAL Project's libcgal library, specifically version 5.1.1. The flaw arises from improper validation of array indices (CWE-129) within the Nef polygon-parsing functionality, particularly in the PM_io_parser<PMDEC>::read_hedge() function located in Nef_2/PM_io_parser.h. This vulnerability allows an attacker to supply a specially crafted malformed input file that triggers out-of-bounds (OOB) reads and type confusion errors. The OOB read occurs when the function e->set_vertex() accesses array elements without proper bounds checking. Such memory corruption can lead to arbitrary code execution, as the type confusion may allow an attacker to manipulate program flow or corrupt memory structures. Exploitation requires the attacker to provide malicious input to the vulnerable parsing function, which is typically invoked when processing polygon data files. There are no known public exploits in the wild, and no official patches or fixes have been linked or published as of the vulnerability disclosure date. The vulnerability affects only the specific CGAL-5.1.1 version of libcgal, which is a computational geometry library widely used in scientific computing, CAD applications, and other geometry-intensive software. The lack of authentication or user interaction requirements means that any system processing untrusted polygon files with this vulnerable library is at risk if exposed to attacker-controlled input.

For European organizations, the impact of this vulnerability depends largely on the usage of CGAL libcgal 5.1.1 within their software stacks. Organizations involved in engineering, CAD design, scientific research, and manufacturing that utilize CGAL for geometric computations could be at risk. Successful exploitation could lead to arbitrary code execution, compromising confidentiality, integrity, and availability of affected systems. This could result in unauthorized access to sensitive design data, intellectual property theft, or disruption of critical engineering workflows. Since the vulnerability can be triggered by processing malicious polygon files, any automated or manual import of such files from external or untrusted sources increases risk. The absence of known exploits reduces immediate threat but does not eliminate risk, especially as attackers may develop exploits over time. The medium severity rating reflects moderate impact potential combined with the need for crafted input and specific library version usage. European organizations with supply chain dependencies on software incorporating CGAL libcgal should be vigilant, as exploitation could propagate through third-party applications.

1. Inventory and Audit: Conduct a thorough inventory of software and systems to identify any usage of CGAL libcgal version 5.1.1, especially in applications processing polygon or geometric data. 2. Update and Patch: Although no official patch is linked, monitor CGAL Project repositories and security advisories for updates or patches addressing this vulnerability. Plan to upgrade to a fixed or newer version of libcgal once available. 3. Input Validation and Sanitization: Implement strict validation and sanitization of all polygon or geometry files before processing, especially those from untrusted or external sources. Reject or quarantine malformed or suspicious files. 4. Application Hardening: Where possible, run vulnerable applications with least privilege, sandboxing, or within containerized environments to limit potential damage from exploitation. 5. Network Controls: Restrict network access to services that process polygon files to trusted users and systems only, reducing exposure to attacker-controlled inputs. 6. Monitoring and Detection: Enable logging and monitoring for unusual application crashes or memory errors related to polygon parsing, which may indicate exploitation attempts. 7. Vendor Engagement: Engage with software vendors or internal development teams to prioritize remediation and communicate risks to stakeholders.