CVE-2020-20451 in FFmpeg
Summary
by MITRE • 05/26/2021
Denial of Service issue in FFmpeg 4.2 due to resource management errors via fftools/cmdutils.c.
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Analysis
by VulDB Data Team • 05/29/2021
The vulnerability CVE-2020-20451 represents a denial of service condition affecting FFmpeg version 4.2, specifically within the fftools/cmdutils.c component of the multimedia processing framework. This issue stems from inadequate resource management practices that fail to properly handle memory allocation and deallocation during command processing operations. The flaw manifests when the application processes certain input parameters or command line arguments that trigger specific code paths within the command utility functions, leading to resource exhaustion or improper cleanup routines that prevent normal application operation.
The technical root cause of this vulnerability lies in improper handling of memory resources and state management within the command processing utilities of FFmpeg. When malicious or malformed input triggers specific processing paths in fftools/cmdutils.c, the application fails to release allocated memory or properly manage computational resources, resulting in progressive resource consumption that eventually leads to system instability or complete application termination. This type of resource management error falls under the CWE-404 category of Improper Resource Management, specifically addressing issues related to memory leaks and resource exhaustion. The vulnerability demonstrates characteristics consistent with CWE-772 which deals with Missing Release of Resource after Effective Lifetime, where allocated resources are not properly deallocated when they are no longer needed.
The operational impact of CVE-2020-20451 extends beyond simple application crashes, as it can be exploited to cause sustained denial of service conditions in systems that rely on FFmpeg for multimedia processing tasks. Attackers can craft specific command line inputs or process sequences that trigger the resource management failure, potentially causing system instability, performance degradation, or complete service interruption. Systems utilizing FFmpeg as part of their multimedia processing pipelines, including content management systems, media servers, and streaming platforms, become vulnerable to this attack vector. The vulnerability can be particularly dangerous in automated environments where FFmpeg is invoked programmatically, as it may lead to cascading failures that affect entire processing workflows.
Mitigation strategies for CVE-2020-20451 should prioritize immediate patching of FFmpeg installations to version 4.3 or later, where the resource management issues have been addressed through improved memory handling and proper cleanup routines. Organizations should implement input validation and sanitization measures to prevent malformed command line arguments from reaching the vulnerable code paths. Network segmentation and access controls can help limit exposure by restricting who can invoke FFmpeg commands or submit processing requests. Additionally, monitoring systems should be configured to detect unusual resource consumption patterns that may indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1499.004 for Resource Hijacking, where adversaries may exploit resource management flaws to consume system resources and cause denial of service conditions. Regular security assessments and vulnerability scanning should include verification of FFmpeg versions and proper configuration to prevent exploitation of this and similar resource management vulnerabilities.