### Impact

The GitHub Actions runner treats certain text in a step's output as commands. The legacy form, `##[command]`, is recognized anywhere in a line. compose-lint's text report prints service names, environment keys and lines of the Compose file, and it does not neutralize `##[`. Inside the compose-lint Action, a Compose file from a pull request can therefore:

- create fake error or warning annotations on the pull request (`##[error]`, `##[warning]`)
- fold the rest of the log, including the real verdict, out of sight (`##[group]`)
- blank out chosen strings for the rest of the log (`##[add-mask]`)

GitHub has postponed removing the deprecated `set-output` log command, so the runner still honors it. A test run of the Action on a GitHub-hosted runner confirmed that a `::set-output` line from a Compose file is processed. Whether it can override the Action's own `sarif-written` output, which decides whether the SARIF upload step runs, has not been tested.

The exit code and the pass/fail result are not affected. Azure Pipelines parses the same `##[` syntax, so the pip package is listed for anyone printing the text report in other CI systems.

Found during an internal pre-1.0 security review.

### Patches

Fixed in 0.31.0. The Action stops the runner from processing workflow commands while compose-lint's output is printed, using a random `stop-commands` token. The text report also escapes `##[`, and `::` at the start of a line, in anything taken from the Compose file.

### Workarounds

- In your own workflow, wrap the compose-lint step in `::stop-commands::<random token>` and `::<random token>::`.
- Use `--format json` or `--format sarif` rather than the text report when linting untrusted pull requests.

### Reproduction

```yaml
services:
web:
image: "nginx:1.25"
environment:
"##[error]DB_PASSWORD": placeholder
"##[group]svc":
image: "nginx:1.25"
privileged: true
```

Run through the Action, this produces a fake error annotation and folds the remaining log lines, including the FAIL verdict, into a collapsed group.