Email hello@attestwire.com. The maintainer reads these directly.

Include what you found, how to reproduce it, and the Action version or commit you were on. Please don't open a public issue for a security report.

There's no bug bounty. If you'd like credit, say so and you'll be named in the release notes for the fix.

Two things this Action touches make it worth a careful look:

The API key. In api mode the key comes in as a GitHub secret. Anything that could put it somewhere it doesn't belong is a security issue — the job log, the job summary, an annotation, an error message, the SARIF report, a crash dump, or an outbound request to a host other than the configured api-url.

Your invoice documents. In api mode the XML is POSTed to the Attestwire API. Invoices carry customer names, addresses, VAT IDs and bank details. Report anything that sends document contents somewhere unintended, or that leaks them into output visible to more people than the person who ran the job.

Also in scope:

• A crafted invoice file, or a crafted files pattern, that reads outside the workspace or writes outside the paths the Action is meant to write.
• Anything that lets file contents or an input string execute as a command or inject workflow commands into the runner's output stream.
• Anything in local mode that makes a network call. Local mode shouldn't make any.

A wrong verdict is a bug. Report it at attestwire/en16931, where the validation logic lives.

Vulnerabilities in the rule engine itself (XML parsing, entity expansion, the PDF reader) belong in that repository's SECURITY.md process, same email either way.