TLDR: depthfirst’s production autonomous security agent discovered 21 zero-day vulnerabilities in FFmpeg, after intensive security analysis by Google and Anthropic. Moving beyond theoretical analysis, our agent produces concrete, reproducible PoC inputs to confirm its findings at a fraction of the costs ($1k vs. $10k). Several of the findings had been sitting latent for 15 to 20 years. We explored the exploitability of the issues and developed a PoC demonstrating a RCE exploit primitive. FFmpeg is one of the most widely deployed pieces of software in the world. From the browsers we use daily to the infrastructure powering the large streaming platforms, it quietly processes media everywhere. As a library that routinely parses complex, untrusted media, it is inherently security critical and a prime target for zero-click attacks.…