Yes, you are responsible for all the code you ship to your users. Not pinning dependencies is asking for trouble. It is literally, "download random code from the Internet and hope for the best."
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EDIT to add: Of course, reaching a state where the whole graph is free of CVEs is a fleeting state of affairs. Staying reasonably up-to-date and using only scanned dependencies is an ongoing process that takes more effort and attention to detail than many projects are willing or able to apply; but it is possible.