Browsertrix is a high-fidelity, browser-based crawling service for web archiving that can be self-hosted or used through Webrecorder's hosted instance. From 1.15.0 until 1.22.8, Browsertrix improperly sanitizes Git URLs specified as Custom Behaviors, allowing command injection through /api/orgs/*/crawlconfigs/validate/custom-behavior. A user with crawler or administrator permission on the specific instance can supply a crafted Git URL that executes arbitrary operating-system commands in the backend pod. Open registration or hosted free-trial access can make the required role broadly obtainable. Successful exploitation can expose, modify, or delete application database records, archived items, browser profiles, storage data, proxy credentials, and other configured service data. This issue is fixed in version 1.22.8.