JVN stands for "the Japan Vulnerability Notes." It is a vulnerability information portal site designed to help ensure Internet security by providing vulnerability information and their solutions for software products used in Japan. JVN is operated jointly by the JPCERT Coordination Center and the Information-technology Promotion Agency (IPA). It's basically Japan's threat intel clearinghouse.

JVN is a vulnerability knowledge-base assisting system administrators and software and other products developers enhance security for their products and customers. Product developers' statements on vulnerabilities include information on affected products, workarounds, and solutions (e.g., updates and patches).

RSS feed: https://jvn.jp/en/rss/jvn.rdf