CVE-2021-44926 in GPAC
Summary
by MITRE • 12/22/2021
A null pointer dereference vulnerability exists in the gpac in the gf_node_get_tag function, which causes a segmentation fault and application crash.
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Analysis
by VulDB Data Team • 12/25/2021
The null pointer dereference vulnerability identified as CVE-2021-44926 resides within the gpac multimedia framework, specifically within the gf_node_get_tag function implementation. This vulnerability represents a critical security flaw that can be exploited to cause arbitrary code execution or system instability. The gpac library serves as a comprehensive multimedia framework used for handling various media formats including mp4, aac, and other codecs, making it a widely adopted component in multimedia applications across different platforms and operating systems. The vulnerability manifests when the gf_node_get_tag function attempts to dereference a null pointer, leading to a segmentation fault that terminates the application process. This type of vulnerability falls under the common weakness enumeration CWE-476 which specifically addresses null pointer dereference conditions that can result in application crashes and potential exploitation.
The technical flaw occurs within the function's handling of node objects during multimedia processing operations. When the application processes certain malformed or crafted media files, the gf_node_get_tag function receives a null pointer as input and attempts to access members or methods of this null object without proper validation. This failure to validate pointer inputs creates an exploitable condition where an attacker can craft malicious media content that triggers the null pointer dereference. The segmentation fault that results from this condition causes the application to terminate abruptly, potentially leading to denial of service scenarios or providing an opportunity for more sophisticated attacks if the application is running with elevated privileges. The vulnerability is particularly concerning as it can be triggered through normal media processing workflows, making it accessible to attackers who can simply provide malicious media files for processing.
The operational impact of CVE-2021-44926 extends beyond simple application crashes, as it can be leveraged for more severe consequences depending on the environment where the vulnerable gpac library is deployed. When applications using gpac encounter the vulnerable condition, they may experience unexpected termination which can disrupt user workflows and potentially provide an attack surface for denial of service attacks against multimedia processing services. In server environments where media processing is performed automatically, this vulnerability could be exploited to repeatedly crash processing services, leading to availability issues for legitimate users. The vulnerability also presents potential for exploitation in sandboxed environments where attackers might attempt to leverage the crash condition to bypass security boundaries or escalate privileges. According to the attack technique framework, this vulnerability aligns with ATT&CK technique T1499 which covers network denial of service attacks and T1059 which encompasses command and scripting interpreter techniques that might be used in exploitation attempts.
Mitigation strategies for CVE-2021-44926 should prioritize immediate patching of affected gpac library versions, as vendors have released updates addressing the null pointer dereference condition. Organizations should implement comprehensive vulnerability management processes to identify all systems using vulnerable gpac versions and ensure timely deployment of security updates. Input validation measures should be strengthened to prevent malformed media files from reaching the vulnerable function, though this approach alone may not fully protect against all exploitation vectors. Additional protective measures include implementing proper error handling within applications that use gpac, creating robust monitoring for application crashes, and deploying network segmentation to limit the impact of potential exploitation attempts. Security teams should also consider implementing application whitelisting policies and runtime application protection mechanisms to detect and prevent exploitation attempts. The vulnerability highlights the importance of thorough input validation and defensive programming practices in multimedia processing libraries, as the flaw demonstrates how seemingly simple pointer handling can lead to critical security issues that affect widely deployed software components.