AIKIDO-2026-897342

TL;DR

On Unix, the crate builds a browser command from the BROWSER environment variable template by substituting the caller-supplied URL into the template and then splitting the entire resulting string on whitespace. When an application opens an externally influenced non-HTTP(S) URL whose parsed form still contains spaces, that content crosses argument boundaries and becomes additional browser argv entries. Injected flags such as --remote-debugging-port or --proxy-server then reach the launched browser, exposing a local debugging endpoint or redirecting browser traffic through an attacker-chosen proxy. The fix tokenizes the template before inserting the URL and passes the URL to the child process exactly once as a single argument.