FFmpeg versions prior to commit 9d786e4 contain a stack buffer overflow in the MPEG-PS muxer (libavformat/mpegenc.c). When an input file is parsed that contains more streams than the muxer's fixed-size stack buffer can hold, the overflow occurs during the creation of the MPEG-PS file header. This flaw can be triggered by an attacker who owns or controls the input file, allowing arbitrary code execution or denial of service if the overflow corrupts critical data structures. The weakness corresponds to an unchecked buffer write (CWE-120 and CWE-121).

The vulnerability impacts the FFmpeg project, affecting all binaries built from source before the commit that introduces the fix (9d786e4b5e9b8482651928574de33772aeee7be1). Users of pre-release or older stable releases should verify the used version. The vulnerability specifically pertains to the MPEG-PS muxer component of FFmpeg.

The CVSS base score is 8.5, indicating a high severity. The EPSS score is less than 1%, indicating a very low likelihood of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog. The likely attack vector is through a crafted media file that contains an excessive number of streams; when ffmpeg processes this file, the stack buffer overflows. The flaw affects the integrity of the program’s execution environment, and an attacker who can provide such a file to ffmpeg can gain local code execution on the host running the process.