Welcome back, cyberwarrior novitiates! In a previous article, we used FFmpeg for streaming camera videos. However, it’s important to keep in mind that FFmpeg is one of the most ubiquitous multimedia processing tools worldwide. It is used in everything from streaming platforms and media servers to desktop applications and mobile software. In this article, I’d […]

The post How to DoS a Media Server: The Memory Leak Vulnerability in ffmpeg (CVE-2025-25469) first appeared on Hackers Arise.

Welcome back, cyberwarrior novitiates!

In a previous article, we used FFmpeg for streaming camera videos. However, it’s important to keep in mind that FFmpeg is one of the most ubiquitous multimedia processing tools worldwide. It is used in everything from streaming platforms and media servers to desktop applications and mobile software.

In this article, I’d like to demonstrate how a memory leak vulnerability in FFmpeg might be exploited to carry out a denial-of-service (DoS) attack on a remote media server or cause resource exhaustion on local client applications.

A Brief History of FFmpeg Vulnerabilities

The project has faced numerous vulnerabilities over the years, ranging from buffer overflows to memory corruption issues that could lead to arbitrary code execution. Previous notable vulnerabilities have included heap-based buffer overflows such as CVE-2020-22029, buffer overflow issues like CVE-2024-32230 with high severity ratings, and CVE-2011-0480 which also carried high severity scores.

The pattern of vulnerabilities in FFmpeg often stems from the complexity of multimedia format parsing and the need to handle malformed or malicious input gracefully. Security risks frequently arise when specially crafted multimedia files are designed to exploit parsing logic, potentially leading to application crashes or arbitrary code execution. Memory management issues, including both buffer overflows and memory leaks like CVE-2025-25469, represent a significant category of these vulnerabilities, often resulting from error handling paths that fail to properly clean up allocated resources.

Understanding CVE-2025-25469

CVE-2025-25469 manifests as a memory leak within the libavutil/iamf.c file, specifically in the IAMF (Immersive Audio Model and Formats) parsing functionality. This vulnerability occurs when the iamf.c component of FFmpeg’s libavutil allocates memory buffers but fails to release them under certain error or edge conditions.

When the av_iamf_parse function encounters a parse failure condition, it returns an error code without freeing the memory buffer that was allocated earlier in the function execution. This creates a situation where each failed parsing attempt consumes system memory that is never reclaimed, leading to gradual memory exhaustion over time.

The vulnerability is particularly concerning because it affects the libavutil component, which serves as a foundational utility library within the FFmpeg ecosystem. This means that any application utilizing FFmpeg’s IAMF processing capabilities could potentially be affected.

Proof-of-Concept: How to Trigger the Leak

To trigger the leak of memory we can create a simple Python script:

Here’s a simple explanation of what the script is doing:

1. The script starts with a Python shebang to run with Python 3.





2. It opens (or creates) a file named bad.iamf in binary write mode.





3. It writes 100 zero bytes into this file. This creates a malformed or invalid IAMF file because a valid IAMF file would not just be zeros.





4. Then, in a loop that runs 1000 times, the script calls the command line to run FFmpeg and process the file bad.iamf each time.





5. The FFmpeg command used suppresses banner output (-hide_banner), attempts to decode the bad.iamf input file (-i bad.iamf), and outputs to null format (-f null -), effectively discarding the output.

As a result we get high CPU usage (around 100%). While the vulnerability is primarily a memory leak in libavutil/iamf.c, it also causes disproportionate CPU load due to the handling of malformed or crafted data. This means the CPU gets heavily utilized attempting to process the invalid input, even though memory consumption may not spike noticeably.

Summary

While the vulnerability itself may seem relatively minor compared to code execution flaws, its potential to cause service disruption and system instability should not be underestimated.

In this article, we explored how, with just a few lines of code, this vulnerability could be exploited, resulting in resource exhaustion. The widespread deployment of FFmpeg across both critical infrastructure and consumer applications makes this issue deserving of immediate attention and remediation.

The post How to DoS a Media Server: The Memory Leak Vulnerability in ffmpeg (CVE-2025-25469) first appeared on Hackers Arise.

Source: HackersArise
Source Link: https://hackers-arise.com/how-to-dos-a-media-server-the-memory-leak-vulnerability-in-ffmpeg-cve-2025-25469/