CVE-2019-20628 in GPAC
Summary
by MITRE
An issue was discovered in libgpac.a in GPAC before 0.8.0, as demonstrated by MP4Box. It contains a Use-After-Free vulnerability in gf_m2ts_process_pmt in media_tools/mpegts.c that can cause a denial of service via a crafted MP4 file.
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Analysis
by VulDB Data Team • 05/11/2025
The vulnerability identified as CVE-2019-20628 represents a critical use-after-free flaw within the GPAC multimedia framework, specifically affecting versions prior to 0.8.0. This issue manifests in the libgpac.a library through the MP4Box utility, which is a core component of the GPAC multimedia toolkit used for processing various digital media formats. The vulnerability stems from improper memory management practices within the gf_m2ts_process_pmt function located in the media_tools/mpegts.c source file, creating a scenario where freed memory locations are accessed after being deallocated, leading to unpredictable behavior and system instability.
The technical exploitation of this vulnerability occurs when a maliciously crafted MP4 file is processed by MP4Box, triggering the use-after-free condition during MPEG-TS (MPEG Transport Stream) processing. This flaw falls under CWE-416, which specifically addresses Use-After-Free vulnerabilities, where program code attempts to access memory after it has been freed by the system. The vulnerability demonstrates how improper memory management can create a path for denial of service attacks, as the application crashes or becomes unresponsive when attempting to process the malformed input file. The exploitation requires minimal user interaction, as simply opening or processing the crafted file is sufficient to trigger the memory corruption.
The operational impact of this vulnerability extends beyond simple denial of service, as it can potentially be leveraged to execute arbitrary code or cause system instability in environments where GPAC is used for media processing. This is particularly concerning in automated media processing systems, content management platforms, or applications that accept user-uploaded media files, where the vulnerability could be exploited to disrupt services or compromise system integrity. The vulnerability affects systems that rely on GPAC for multimedia processing, including video streaming platforms, digital media players, and content creation tools that utilize the MP4Box utility for format conversion or analysis. The issue has been classified under the ATT&CK technique T1499.004 for Evasion through Application or System Exploitation, as it represents a method of system compromise through exploitation of application-level vulnerabilities.
Mitigation strategies for CVE-2019-20628 primarily focus on immediate version upgrading to GPAC 0.8.0 or later, which includes the necessary memory management fixes to prevent the use-after-free condition. Organizations should implement input validation measures to filter or reject suspicious MP4 files before processing, particularly in environments where user-uploaded content is accepted. Additionally, deploying network segmentation and access controls can limit the potential impact of exploitation attempts, while regular security audits should verify that all instances of GPAC are updated to secure versions. System monitoring should be implemented to detect unusual resource consumption or application crashes that may indicate exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date multimedia frameworks and implementing robust memory safety practices in media processing applications.