In the git-tag-annotation-action (open source GitHub Action) before version 1.0.1, an attacker can execute arbitrary (*) shell commands if they can control the value of [the "tag" input] or manage to alter the value of [the "GITHUB_REF" environment variable]. The problem has been patched in version 1.0.1. If you don't use the "tag" input you are most likely safe. The "GITHUB_REF" environment variable is protected by the GitHub Actions environment so attacks from there should be impossible. If you must use the "tag" input and cannot upgrade to "> 1.0.0" make sure that the value is not controlled by another Action.