CVE-2020-28589 in tinyobjloader
Summary
by MITRE • 08/11/2021
An improper array index validation vulnerability exists in the LoadObj functionality of tinyobjloader v2.0-rc1 and tinyobjloader development commit 79d4421. A specially crafted file could lead to code execution. An attacker can provide a malicious file to trigger this vulnerability.
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Analysis
by VulDB Data Team • 08/16/2021
The vulnerability identified as CVE-2020-28589 represents a critical improper array index validation flaw within the tinyobjloader library version 2.0-rc1 and its development commit 79d4421. This library serves as a lightweight OBJ file loader widely utilized in computer graphics applications, 3d modeling software, and game engines for parsing wavefront obj files. The issue manifests specifically within the LoadObj functionality where the library fails to properly validate array indices during the parsing process of malformed input files. When processing specially crafted OBJ files, the library attempts to access memory locations beyond the allocated array boundaries, creating a classic buffer overflow condition that can be exploited by malicious actors.
The technical nature of this vulnerability aligns with CWE-129, which describes improper validation of array indices, and CWE-787, which covers out-of-bounds write operations. The flaw occurs because the tinyobjloader library does not adequately verify the bounds of array access operations when parsing vertex, normal, or texture coordinate data from OBJ files. Attackers can construct malicious OBJ files containing malformed data structures that cause the parser to compute invalid array indices, leading to memory corruption that can be leveraged for arbitrary code execution. This vulnerability operates at the intersection of input validation failures and memory safety issues, making it particularly dangerous in applications that process untrusted 3d model data from external sources.
The operational impact of CVE-2020-28589 extends across numerous applications that depend on the tinyobjloader library, including but not limited to 3d modeling tools, game engines, computer graphics applications, and any software that processes wavefront obj files. An attacker exploiting this vulnerability could gain complete control over the affected system, potentially leading to data theft, system compromise, or denial of service conditions. The attack surface is particularly broad given that OBJ files are commonly used in 3d graphics workflows and can be embedded in various digital content delivery systems. This vulnerability can be triggered through simple file manipulation, making it accessible to attackers with minimal technical expertise, and the exploitation can occur during routine file loading operations without user interaction.
Mitigation strategies for CVE-2020-28589 should prioritize immediate patching of affected versions of the tinyobjloader library to version 2.0-rc2 or later, which contains the necessary fixes for array index validation. Organizations should implement defensive programming practices including input sanitization, bounds checking, and memory safety validations when processing external file formats. Additionally, deployment of runtime protections such as address space layout randomization, stack canaries, and data execution prevention mechanisms can help reduce the exploitability of similar vulnerabilities. The ATT&CK framework categorizes this vulnerability under T1203, which covers exploitation for privilege escalation, and T1059, covering command and scripting interpreter usage, as attackers may leverage the code execution capability for further system compromise. Security monitoring should include detection of unusual file processing patterns and memory access violations that may indicate exploitation attempts against vulnerable applications.