CVE-2019-12481 in GPAC
Summary
by MITRE
An issue was discovered in GPAC 0.7.1. There is a NULL pointer dereference in the function GetESD at isomedia/track.c in libgpac.a, as demonstrated by MP4Box.
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Analysis
by VulDB Data Team • 03/14/2025
The vulnerability identified as CVE-2019-12481 represents a critical NULL pointer dereference flaw within the GPAC multimedia framework version 0.7.1. This issue specifically affects the GetESD function located in the isomedia/track.c file of the libgpac.a library, which is extensively utilized by the MP4Box utility for multimedia file processing and manipulation. The flaw manifests when the application processes malformed or specially crafted MP4 files that contain invalid Elementary Stream Descriptors, creating a scenario where the function attempts to dereference a null pointer during normal operation. This vulnerability exists within the broader context of multimedia processing software where proper input validation and error handling mechanisms are essential for maintaining system stability and preventing potential exploitation.
The technical implementation of this vulnerability stems from inadequate null pointer checks within the GetESD function, which is responsible for extracting Elementary Stream Descriptors from ISO media files. When MP4Box encounters a malformed MP4 file structure, the function fails to properly validate pointer references before accessing memory locations, resulting in a segmentation fault or application crash. This type of flaw falls under CWE-476 which specifically addresses NULL pointer dereference conditions in software implementations. The vulnerability demonstrates a classic lack of defensive programming practices where the code assumes certain pointers will always contain valid references without proper validation checks. The flaw can be triggered through simple file manipulation techniques that create malformed MP4 structures, making it particularly dangerous as it requires minimal user interaction to exploit.
From an operational perspective, this vulnerability poses significant risks to multimedia processing environments where GPAC libraries are extensively used for video encoding, decoding, and file conversion tasks. The NULL pointer dereference can lead to complete application crashes, potentially disrupting media processing workflows and causing data loss in automated systems. Attackers could exploit this vulnerability by crafting malicious MP4 files that trigger the crash when processed by MP4Box or any application relying on the vulnerable GPAC library. This creates a potential denial of service scenario that could be particularly problematic in server environments or automated media processing pipelines where system availability is critical. The vulnerability also aligns with ATT&CK technique T1203 which involves exploiting software vulnerabilities to cause system instability or disruption, and T1059 which covers command and control through compromised systems.
Mitigation strategies for CVE-2019-12481 should prioritize immediate patching of the GPAC library to version 0.7.2 or later, which contains the necessary fixes for the NULL pointer dereference issue. Organizations should implement input validation measures that sanitize all MP4 files before processing them through GPAC-based applications, particularly in automated environments where untrusted input is common. Network administrators should consider implementing file type restrictions and content filtering mechanisms to prevent potentially malicious MP4 files from reaching processing systems. Additionally, system administrators should monitor for abnormal application behavior or crashes that might indicate exploitation attempts. The fix implemented in newer versions of GPAC addresses the root cause by adding proper null pointer validation before memory access operations, ensuring that the GetESD function gracefully handles malformed input rather than crashing. Security teams should also consider implementing runtime monitoring solutions that can detect and alert on suspicious pointer access patterns that might indicate similar vulnerabilities in other parts of the multimedia processing stack.