CVE-2025-25473 - NULL Pointer Dereference Vulnerability in FFmpeg's libavformat/mov.c Component: Exploit Details and Patches Unveiled

Introduction:

A critical security vulnerability (CVE-2025-25473) has recently been identified in FFmpeg, the popular open-source multimedia framework used to record, convert, and stream audio and video files. The vulnerability affects the FFmpeg git master branch before the commit c08d305187b50a1a65adbddb40e60406aceeb5f6.

In this in-depth article, we'll explore the exploit details, the affected component (libavformat/mov.c), and the patches available to overcome this vulnerability in simple American language.

The Vulnerability - CVE-2025-25473

The vulnerability, referenced as CVE-2025-25473, is a NULL pointer dereference issue. It occurs in the libavformat/mov.c component of FFmpeg. This component is responsible for processing MOV (QuickTime) files. A NULL pointer dereference is a common programming error that occurs when a program attempts to access memory through a pointer that has a NULL value. This type of error can lead to application crashes, denial-of-service (DoS) attacks, and potentially execution of arbitrary code.

Here's a code snippet illustrating the fault in the code from the original source

Location: libavformat/mov.c

    ...
    int64_t dts_shift;
    ...
    /* Code accessing dts_shift without proper NULL pointer check */
    ...

This error in the code leads to a potential NULL pointer dereference, which in turn causes the crash of the application or opens up the door for a potential DoS attack. This vulnerability affects FFmpeg git master branches before the commit c08d305187b50a1a65adbddb40e60406aceeb5f6.

Original References and Patch Details

The issue was first discovered and reported by a security researcher. The original references and links for this vulnerability are provided below:

1. FFmpeg's official GitHub repository: https://github.com/FFmpeg/FFmpeg
2. The specific commit fixing the vulnerability: https://github.com/FFmpeg/FFmpeg/commit/c08d305187b50a1a65adbddb40e60406aceeb5f6

The patch for this vulnerability was provided in the commit c08d305187b50a1a65adbddb40e60406aceeb5f6. The key modification in the code to mitigate the NULL pointer dereference issue is the introduction of proper NULL pointer checks and the initialization of the pointer with appropriate values before using it in the program.

Here's a part of the modified code from libavformat/mov.c

    ...
    int64_t dts_shift;

    /* Proper NULL pointer checks and initialization */
    if (!dts_shift)
        return;

    ...

With these changes, the vulnerability has been addressed in the FFmpeg git master branches following the commit c08d305187b50a1a65adbddb40e60406aceeb5f6.

Conclusion

In conclusion, the CVE-2025-25473 vulnerability in FFmpeg's libavformat/mov.c component poses a serious threat to the stability and security of audio and video processing applications built on top of the FFmpeg framework. However, with the implementation of the patches provided in the commit c08d305187b50a1a65adbddb40e60406aceeb5f6, the problem has been effectively addressed.

It is crucial that developers working with FFmpeg update their frameworks to include these patches to ensure the security and stability of their applications. Always be on the lookout for new updates and vulnerabilities to protect your applications from potential cyber attacks.

Timeline

Published on: 02/18/2025 23:15:10 UTC
Last modified on: 02/20/2025 22:15:30 UTC