Versions of conflibot before "1.2.1" build "git" commands by string interpolation and run them through a shell. Several of the interpolated values are pull request branch names ("head.ref"), which are attacker-controlled: anyone can open a pull request (including from a fork) whose head branch name contains shell metacharacters such as "`", "$( )", ";", "|", or "&". The recommended workflow runs conflibot on the "pull_request_target" event, where the job has access to the base repository's secrets and a write-scoped "GITHUB_TOKEN". As a result, a crafted branch name causes arbitrary command execution on the runner with that write token in the environment, allowing an attacker to exfiltrate secrets and the token, push to the repository, or otherwise abuse the token's permissions. No special privileges and no maintainer interaction are required — the action runs automatically when the pull request is opened.