CVE-2026-54732: libreoffice-convert vulnerable to path traversal / arbitrary file write

options.fileName is used to build a filesystem path (path.join(tempDir.name, fileName)) and the caller-supplied document buffer is written there, but fileName is never reduced to a base name. A fileName containing “../” escapes the temporary directory, so a caller can write arbitrary content to an arbitrary path the process can write to (e.g. ~/.ssh/authorized_keys, an /etc/cron.d entry, or a web root).