File upload vulnerabilities are often treated as low-severity issues, but in modern cloud-native environments they can deliver total compromise. In early 2025, researchers discovered a flaw in the open source Streamlit’s widely adopted st.file_uploader widget that allowed a simple client-side check to be bypassed, leading to arbitrary file uploads and complete control of misconfigured cloud instances.

This session walks through the full exploit chain, showing how attackers can weaponize this overlooked feature. By intercepting upload traffic and injecting payloads, we demonstrate how to bypass file-type filtering, achieve directory traversal, and overwrite .ssh/authorized_keys to gain persistent remote access. From there, we pivot into the cloud environment, enumerating roles and manipulating data pipelines powering real-time stock dashboards.

This will be a live proof-of-concept session demoing how this vulnerability could enable market manipulation, data tampering, and other high-impact attacks. Beyond the immediate exploit, the talk exposes a broader pattern: how misplaced trust in frontend logic and cloud misconfigurations create reliable attack surfaces in open-source frameworks.