CVE-2020-28623: 
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-2020-28623, specifically involves an out-of-bounds read vulnerability in NefS2/SNCioparser.h SNCioparser::readfacet() fh->twin(). This vulnerability was discovered and disclosed in February 2021, affecting the CGAL library's geometric algorithms and data structures (Talos Report).

The vulnerability stems from improper validation of array indices in the Nef polygon-parsing code. When parsing files containing Nef polygon data, the code fails to properly validate indices before using them as vector indices, which can result in out-of-bounds reads and type confusion. The vulnerability has been assigned a CVSS v3.1 base score of 8.8 HIGH (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) by NIST NVD, while Talos assessed it with a CVSS score of 10.0 CRITICAL (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H). The vulnerability is classified under CWE-125 (Out-of-bounds Read) and CWE-129 (Improper Validation of Array Index) (NVD).

The vulnerability can lead to arbitrary code execution when processing specially crafted malformed files. An attacker can trigger the vulnerability by providing malicious input, potentially leading to out-of-bounds reads and type confusion, which could ultimately result in code execution (Debian LTS).

Users are advised to upgrade to a patched version of CGAL. For Debian 10 (buster), the fix was implemented in version 4.13-1+deb10u1. Gentoo users should upgrade to version 5.4.1 or later (Debian LTS, Gentoo Security).