CVE-2020-28613: 
Linux Debian vulnerability analysis and mitigation

Multiple code execution vulnerabilities exist in the Nef polygon-parsing functionality of CGAL libcgal CGAL-5.1.1. The vulnerability, identified as CVE-2020-28613, specifically involves an out-of-bounds read vulnerability in NefS2/SNCioparser.h SNCioparser::readvertex() vh->sverticeslast(). A specially crafted malformed file can lead to an out-of-bounds read and type confusion, which could lead to code execution ([Talos Intelligence](https://talosintelligence.com/vulnerabilityreports/TALOS-2020-1225), NVD).

The vulnerability is classified under CWE-129 (Improper Validation of Array Index) and CWE-125 (Out-of-bounds Read). The issue occurs in the vertex handling functionality where the code fails to properly validate array indices before accessing them. The vulnerable code path is triggered during the parsing of Nef polygon data, specifically in the SNCioparser::readvertex() function when accessing vh->sverticeslast(). The vulnerability allows an attacker to cause an out-of-bounds read condition through specially crafted input (NVD CVMAP).

The vulnerability can lead to code execution through out-of-bounds read and type confusion when processing specially crafted malformed files. This poses a significant security risk as it could allow attackers to execute arbitrary code by providing malicious input (Debian LTS).

The vulnerability has been addressed in subsequent versions of CGAL. Users are recommended to upgrade to a patched version. For Debian 10 (buster), the fix is available in version 4.13-1+deb10u1. For Gentoo users, upgrading to version 5.4.1 or later is recommended (Debian LTS, Gentoo Security).