CVE-2021-38092 in FFmpeg
Summary
by MITRE • 09/20/2021
Integer Overflow vulnerability in function filter_prewitt in libavfilter/vf_convolution.c in Ffmpeg 4.2.1, allows attackers to cause a Denial of Service or other unspecified impacts.
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Analysis
by VulDB Data Team • 09/29/2021
The integer overflow vulnerability identified as CVE-2021-38092 resides within the FFmpeg multimedia framework version 4.2.1, specifically within the libavfilter/vf_convolution.c module. This flaw manifests in the filter_prewitt function which processes convolution operations for image filtering. The vulnerability arises from insufficient input validation and arithmetic overflow handling when processing certain parameters that control the convolution matrix dimensions. When an attacker provides carefully crafted input parameters, the function fails to properly validate the integer values, leading to arithmetic overflow conditions that can corrupt memory structures and cause unpredictable behavior.
The technical implementation of this vulnerability stems from the convolution filter's handling of matrix dimensions where integer overflow occurs during calculations involving width and height parameters. According to CWE-190, this represents an integer overflow condition that can result in memory corruption and arbitrary code execution. The flaw specifically impacts the prewitt edge detection filter which is commonly used in video processing pipelines for feature extraction and image enhancement. The vulnerability is particularly concerning because it can be triggered through normal media processing operations without requiring special privileges, making it accessible to remote attackers who can craft malicious media files.
Operationally, this vulnerability creates significant risks for systems that rely on FFmpeg for media processing, including content delivery networks, video streaming platforms, and multimedia applications. The denial of service impact can cause system crashes or hangs during video processing, disrupting services and potentially leading to availability issues for end users. Additionally, the unspecified impacts mentioned in the CVE description suggest potential for more severe consequences including information disclosure or privilege escalation depending on the execution context. The vulnerability affects both local and remote attack scenarios, making it particularly dangerous in environments where untrusted media content is processed automatically.
Mitigation strategies for CVE-2021-38092 should prioritize immediate patching of FFmpeg installations to versions 4.4 or later where the integer overflow has been addressed. System administrators should implement input validation controls and sanitize all media files before processing through FFmpeg pipelines. Network segmentation and access controls can limit exposure by restricting direct access to media processing systems. Monitoring solutions should be deployed to detect abnormal processing patterns that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1203, which involves exploitation of software vulnerabilities for system compromise, and represents a common vector for attackers seeking to disrupt services through denial of service conditions. Organizations should also consider implementing sandboxing mechanisms for media processing to contain potential exploitation impacts and maintain compliance with security standards such as those outlined in NIST SP 800-144 for multimedia security practices.