CVE-2021-44923 in GPAC
Summary
by MITRE • 12/22/2021
A null pointer dereference vulnerability exists in gpac 1.1.0 in the gf_dump_vrml_dyn_field.isra function, which causes a segmentation fault and application crash.
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Analysis
by VulDB Data Team • 03/18/2025
The null pointer dereference vulnerability identified as CVE-2021-44923 affects the gpac 1.1.0 media processing library, specifically within the gf_dump_vrml_dyn_field.isra function. This vulnerability represents a critical security flaw that can be exploited to cause application instability and potential denial of service conditions. The issue manifests when the application attempts to access a null pointer during VRML (Virtual Reality Modeling Language) file processing operations, leading to a segmentation fault that terminates the process. Such vulnerabilities are particularly concerning in media processing software as they can be triggered through malformed input files, making them attractive targets for attackers seeking to disrupt services or execute malicious payloads.
The technical root cause of this vulnerability lies in improper input validation and error handling within the VRML file parsing functionality of the gpac library. When processing certain VRML structures, the gf_dump_vrml_dyn_field.isra function fails to properly validate pointer references before dereferencing them, creating an opportunity for a null pointer dereference condition. This flaw aligns with CWE-476, which specifically addresses null pointer dereference vulnerabilities in software implementations. The vulnerability demonstrates poor defensive programming practices where the application does not adequately check for null values before attempting to access memory locations, a fundamental security principle that should be enforced throughout all code paths.
The operational impact of CVE-2021-44923 extends beyond simple application crashes, as it can be leveraged to create denial of service conditions that affect media processing services and applications relying on gpac for content handling. Attackers can craft malicious VRML files that trigger this vulnerability, potentially causing cascading failures in systems that depend on continuous media processing capabilities. The segmentation fault resulting from this vulnerability can be exploited in various attack scenarios, including web application exploitation where users upload media content, or in server-side processing environments where automated media conversion occurs. This vulnerability particularly affects systems implementing the attack pattern described in the MITRE ATT&CK framework under T1499.004, which covers network denial of service attacks targeting application availability.
Mitigation strategies for CVE-2021-44923 should prioritize immediate patching of affected gpac installations to version 1.1.1 or later, which contains the necessary fixes for the null pointer dereference condition. Organizations should implement robust input validation mechanisms that sanitize all VRML content before processing, particularly when dealing with user-uploaded media files. Additionally, deploying application-level protections such as memory protection mechanisms, stack canaries, and address space layout randomization can help mitigate exploitation attempts. System administrators should monitor for unusual application crash patterns and implement intrusion detection systems that can identify potential exploitation attempts. The vulnerability also highlights the importance of regular security audits and code reviews focusing on pointer validation and error handling practices, particularly in libraries that process untrusted input data. Organizations should consider implementing sandboxing techniques for media processing operations to contain potential exploitation impacts and reduce the attack surface available to adversaries targeting this class of vulnerability.