tj-actions/branch-names is a Github actions repository that contains workflows to retrieve branch or tag names with support for all events. In versions 8.2.1 and below, a critical vulnerability has been identified in the tj-actions/branch-names' GitHub Action workflow which allows arbitrary command execution in downstream workflows. This issue arises due to inconsistent input sanitization and unescaped output, enabling malicious actors to exploit specially crafted branch names or tags. While internal sanitization mechanisms have been implemented, the action outputs remain vulnerable, exposing consuming workflows to significant security risks. This is fixed in version 9.0.0

tj-actions/branch-names is a Github action to retrieve branch or tag names with support for all events. The `tj-actions/branch-names` GitHub Actions improperly references the `github.event.pull_request.head.ref` and `github.head_ref` context variables within a GitHub Actions `run` step. The head ref variable is the branch name and can be used to execute arbitrary code using a specially crafted branch name. As a result an attacker can use this vulnerability to steal secrets from or abuse `GITHUB_TOKEN` permissions. This vulnerability has been addressed in version 7.0.7. Users are advised to upgrade. There are no known workarounds for this vulnerability.