CVE-2021-44919 in GPAC
Summary
by MITRE • 12/22/2021
A Null Pointer Dereference vulnerability exists in the gf_sg_vrml_mf_alloc function, which causes a segmentation fault and application crash.
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Analysis
by VulDB Data Team • 12/25/2021
The vulnerability identified as CVE-2021-44919 represents a critical null pointer dereference flaw within the gf_sg_vrml_mf_alloc function of a graphics rendering library. This issue manifests when the application attempts to access a memory location through a null pointer reference, leading to an immediate segmentation fault and subsequent application crash. The flaw occurs during the allocation process of VRML (Virtual Reality Modeling Language) multi-field data structures, specifically within the graphics subsystem responsible for handling 3D model rendering and manipulation. The vulnerability demonstrates characteristics consistent with CWE-476, which describes null pointer dereference conditions that can result in program termination and denial of service.
The technical implementation of this vulnerability stems from inadequate input validation and memory management within the VRML parsing component. When processing malformed or specially crafted VRML files, the gf_sg_vrml_mf_alloc function fails to properly initialize or validate pointer references before attempting to dereference them. This flaw can be triggered through various attack vectors including malicious file uploads, web-based VRML content execution, or improper handling of user-supplied 3D model data. The segmentation fault occurs because the function attempts to access memory through a pointer that has not been properly allocated or assigned a valid memory address, causing the operating system to terminate the application process and generate a crash report.
The operational impact of CVE-2021-44919 extends beyond simple application instability, presenting significant risks to system availability and user experience. In environments where graphics rendering applications are critical for operations, such as CAD software, 3D modeling platforms, or virtual reality applications, this vulnerability can lead to complete service disruption. Attackers could exploit this flaw to perform denial of service attacks against legitimate users, causing repeated application crashes and forcing system administrators to restart services or reboot systems. The vulnerability is particularly concerning in server environments where multiple users might interact with the graphics processing system, as it could enable an attacker to systematically disrupt service availability through repeated exploitation attempts.
Mitigation strategies for CVE-2021-44919 should focus on immediate patch application and input validation improvements. System administrators should prioritize updating the affected graphics library to the latest version containing the patched gf_sg_vrml_mf_alloc function that properly validates pointer references before dereferencing. Additionally, implementing robust input sanitization measures can help prevent malformed VRML content from reaching the vulnerable function, including MIME type validation, file size limits, and content scanning for suspicious patterns. Network-level protections such as web application firewalls and intrusion prevention systems can also provide additional layers of defense by monitoring for known exploit patterns and blocking malicious VRML content before it reaches the vulnerable application. From an ATT&CK perspective, this vulnerability aligns with T1499.004 which covers network disruption attacks, and T1566.001 which addresses spearphishing with malicious attachments, as the exploit could be delivered through malicious VRML files in email attachments or web downloads.