CVE-2023-51794

What it actually does

Buffer overflow in libavfilter/af_stereowiden.c:120 allows an attacker-supplied value to overwrite adjacent stack memory, enabling arbitrary code execution in the context of the FFmpeg process.

Why it matters to the business

Systems that process untrusted media files with FFmpeg can be fully compromised by an attacker who already has the ability to run code or supply files locally, leading to loss of confidentiality, integrity, and availability on media-processing hosts.

How an attack unfolds

An attacker supplies a specially crafted audio or video file that exercises the stereowiden filter; the malformed parameter triggers an out-of-bounds write that overwrites return addresses or function pointers, allowing shellcode execution when the filter processes the frame.

How to fix it

Upgrade FFmpeg to a version containing the fix for the stereowiden buffer overflow; rebuild any locally compiled installations or containers with the patched source; disable the stereowiden filter via AVOptions where upgrade is not immediately possible.

How to confirm the fix worked

Confirm the installed FFmpeg version is newer than the vulnerable commit; run regression tests that exercise af_stereowiden with boundary values; monitor for crashes or sanitizer violations when processing crafted test files.

Typical attack path

1. Obtain local execution or file-write access on a host running FFmpeg
2. Place or stream a malicious media file that invokes the stereowiden filter
3. Trigger FFmpeg to decode or filter the file (via command line, library call, or application)
4. Exploit the resulting buffer overflow to gain arbitrary code execution

How to detect it

Search process execution logs and command-line audit trails for invocations of FFmpeg that include the stereowiden filter; inspect core dumps or sanitizer reports for stack-smashing indicators near af_stereowiden; correlate with file-creation events of media files immediately preceding abnormal FFmpeg termination.

What your security team should do

• Prioritize patching FFmpeg on any internet-facing or multi-tenant media-processing systems
• Restrict local execution of FFmpeg to trusted users and inputs only
• Add FFmpeg version checks to software bill-of-materials and container scanning pipelines
• Review applications that invoke FFmpeg with user-supplied filters for additional hardening