CVE-2025-25473 in FFmpeg
Summary
by MITRE • 02/19/2025
FFmpeg git master before commit c08d30 was discovered to contain a memory leak in the avformat_free_context function in libavutil/mem.c.
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Analysis
by VulDB Data Team • 01/02/2026
The vulnerability identified as CVE-2025-25473 represents a critical memory management flaw within the FFmpeg multimedia framework that affects versions prior to commit c08d30 in the git master branch. This issue specifically targets the avformat_free_context function located in libavutil/mem.c, which serves as a fundamental component for managing memory allocation and deallocation within the FFmpeg library ecosystem. The memory leak occurs during the cleanup process of format context structures, which are essential for handling multimedia file parsing and demuxing operations across various audio and video formats.
The technical flaw manifests when the avformat_free_context function fails to properly release all allocated memory segments associated with a format context, leading to gradual memory consumption that can eventually result in system resource exhaustion. This memory leak vulnerability stems from incomplete memory deallocation logic within the function implementation, where certain memory blocks allocated during format context initialization are not properly freed during the cleanup phase. The issue is particularly concerning because format contexts are routinely created and destroyed during multimedia processing operations, making this leak potentially exploitable through repeated usage patterns or prolonged system operation.
From an operational impact perspective, this vulnerability creates significant risks for applications and systems that rely heavily on FFmpeg for multimedia processing tasks. The memory leak can lead to progressive system performance degradation, application crashes, or complete system instability when applications repeatedly create and destroy format contexts without proper memory management. Attackers could potentially exploit this weakness by crafting malicious multimedia files or by triggering repeated format context creation scenarios to exhaust available memory resources, resulting in denial of service conditions that affect both the targeted application and underlying system stability. The vulnerability aligns with CWE-401, which specifically addresses memory leaks in software systems, and could be categorized under ATT&CK technique T1499.004 for resource exhaustion attacks.
Mitigation strategies for this vulnerability should prioritize immediate application of the patch released in commit c08d30 or equivalent fixes that ensure complete memory deallocation within the avformat_free_context function. System administrators should implement monitoring solutions to detect abnormal memory usage patterns that may indicate exploitation attempts, while application developers should review their FFmpeg integration code to ensure proper context management and implement additional memory leak detection mechanisms. The fix typically involves correcting the memory deallocation logic to ensure all allocated memory segments, including those in nested structures and associated metadata, are properly freed during the context cleanup process. Organizations should also consider implementing automated memory leak detection tools and regular security audits of multimedia processing applications to prevent similar issues from emerging in other components of their software stack.