Legcord 1.1.0 through 1.3.0 contains a path traversal vulnerability in theme IPC handlers that allows script in the Discord page to escape the themes directory via unvalidated theme ids. Attackers running script in the Discord origin, such as through XSS, can abuse themes.folder, themes.uninstall, and themes.install to launch local executables, recursively delete directories, and write files outside the themes directory.

Legcord 1.1.0 through 1.3.0 contains a configuration injection vulnerability that allows script in the Discord page to write any config key via the window.legcord settings.setConfig bridge. Attackers exploiting a Discord XSS can set additionalArguments to persistently add --proxy-server and --ignore-certificate-errors switches, routing all client traffic through an interception proxy.