CVE-2009-4636 in FFmpeg
Summary
by MITRE
FFmpeg 0.5 allows remote attackers to cause a denial of service (hang) via a crafted file that triggers an infinite loop.
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Analysis
by VulDB Data Team • 04/30/2026
The vulnerability identified as CVE-2009-4636 represents a critical denial of service flaw within FFmpeg version 0.5, a widely used multimedia framework that processes audio and video files across numerous applications and platforms. This vulnerability specifically targets the decoding functionality of FFmpeg, where a maliciously crafted media file can trigger an infinite loop in the processing pipeline, causing the application to hang indefinitely. The flaw occurs during the parsing and decoding stages when the software encounters malformed input data that disrupts normal execution flow, leading to resource exhaustion and system unresponsiveness.
The technical implementation of this vulnerability stems from inadequate input validation and error handling within FFmpeg's media file parser. When processing certain crafted files, the decoder enters a condition where it repeatedly executes the same set of instructions without proper termination conditions, creating an infinite loop that consumes system resources and prevents further processing. This behavior aligns with CWE-835, which specifically addresses infinite loops or iterations that can lead to denial of service conditions. The vulnerability affects the core decoding logic and demonstrates poor defensive programming practices where boundary conditions and malformed input scenarios were not adequately considered during development.
From an operational perspective, this vulnerability presents significant risks to systems that rely on FFmpeg for media processing, including content management systems, video streaming platforms, and multimedia applications. Attackers can exploit this flaw by uploading or transmitting specially crafted media files that, when processed by FFmpeg, cause the target system to become unresponsive. The impact extends beyond simple service disruption as the hanging process can consume substantial CPU and memory resources, potentially affecting other applications running on the same system. This vulnerability can be particularly dangerous in automated processing environments where batch operations are common, as a single malicious file can cause cascading failures throughout the processing pipeline.
The exploitation of CVE-2009-4636 aligns with ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion. Organizations utilizing FFmpeg in their multimedia processing workflows face substantial operational risks, as this vulnerability can be leveraged to perform low-cost denial of service attacks that require minimal technical expertise. The vulnerability's impact is amplified by FFmpeg's widespread adoption across various platforms and applications, making it a prime target for attackers seeking to disrupt services. System administrators and security professionals must consider this vulnerability when implementing security controls for multimedia processing environments.
Mitigation strategies for this vulnerability primarily involve immediate patching of FFmpeg installations to versions that contain fixes for the infinite loop condition. Organizations should also implement input validation and sanitization measures at the application level, particularly when handling user-uploaded media files. Additionally, deploying monitoring systems that can detect resource exhaustion and process hanging conditions can provide early warning of potential exploitation attempts. Network-level controls such as rate limiting and file type validation can help prevent malicious files from reaching the FFmpeg processing layer. The vulnerability underscores the importance of comprehensive input validation and robust error handling in multimedia processing libraries, as recommended by security best practices and industry standards for preventing similar denial of service conditions.