CVE-2020-28622 in CGAL
Summary
by MITRE • 04/18/2022
Multiple code execution vulnerabilities exists in the Nef polygon-parsing functionality of CGAL libcgal CGAL-5.1.1. A specially crafted malformed file can lead to an out-of-bounds read and type confusion, which could lead to code execution. An attacker can provide malicious input to trigger any of these vulnerabilities. An oob read vulnerability exists in Nef_S2/SNC_io_parser.h SNC_io_parser<EW>::read_edge() eh->incident_sface().
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Analysis
by VulDB Data Team • 04/18/2022
The vulnerability under discussion represents a critical security flaw within the computational geometry library CGAL, specifically affecting its polygon-parsing capabilities in version 5.1.1. This issue stems from insufficient input validation mechanisms within the Nef polygon functionality, which is part of the larger libcgal library suite. The vulnerability manifests through multiple code execution pathways that can be exploited by malicious actors who craft specially formatted input files designed to trigger memory corruption conditions.
The technical exploitation occurs through a combination of out-of-bounds read conditions and type confusion vulnerabilities present in the Nef_S2/SNC_io_parser.h component, specifically within the SNC_io_parser< EW >::read_edge() method. When processing malformed input data, the parser fails to properly validate array indices and memory access patterns, leading to unauthorized memory reads beyond allocated boundaries. This out-of-bounds read condition creates a type confusion scenario where the application incorrectly interprets memory contents as different data types than originally intended.
The operational impact of this vulnerability extends far beyond simple denial of service conditions, as it provides attackers with potential code execution capabilities through carefully crafted input files. The vulnerability exists within the SNC_io_parser::read_edge() function where the expression eh->incident_sface() accesses memory locations without proper bounds checking, allowing adversaries to manipulate memory layouts and potentially redirect program execution flow. This represents a classic buffer overflow condition that can be leveraged for arbitrary code execution in the context of applications utilizing CGAL's Nef polygon functionality.
Security researchers have identified this vulnerability as mapping to CWE-125 (Out-of-bounds Read) and CWE-476 (NULL Pointer Dereference) within the Common Weakness Enumeration catalog, while also aligning with ATT&CK techniques involving privilege escalation through code injection. The attack surface is particularly concerning given that CGAL is widely used in computational geometry applications including CAD software, geographic information systems, and scientific computing platforms where polygon processing is fundamental to core operations.
Mitigation strategies should focus on implementing comprehensive input validation mechanisms within the parser component, adding bounds checking for all memory access operations, and applying defensive programming practices such as stack canaries and address space layout randomization. Additionally, users should consider upgrading to patched versions of CGAL, implementing strict input sanitization procedures, and deploying runtime monitoring solutions to detect anomalous memory access patterns that might indicate exploitation attempts.
The vulnerability demonstrates the critical importance of robust memory management in computational geometry libraries where mathematical operations require precise handling of geometric data structures. Applications leveraging CGAL's Nef polygon functionality must undergo thorough security assessments to identify potential attack vectors, while developers should implement comprehensive testing procedures including fuzzing against malformed input files to prevent similar vulnerabilities from emerging in future releases.
Organizations using affected versions of CGAL should immediately evaluate their exposure through vulnerability scanning and penetration testing activities. The remediation process involves not only updating library components but also reviewing application code that interfaces with CGAL functions to ensure proper error handling and input validation mechanisms are implemented at multiple layers of the software stack. This vulnerability serves as a reminder of the critical security considerations required when developing mathematical computing libraries that handle user-provided geometric data in production environments.