Flowsint is an open-source OSINT graph exploration tool designed for cybersecurity investigation, transparency, and verification. Prior to 1.2.3, Flowsint allows a user to create investigations, which are used to manage sketches and analyses. Sketches have controllable graphs, which are comprised of nodes and relationships. The sketches contain information on an OSINT target (usernames, websites, etc) within these nodes and relationships. A remote attacker can create a node with a malicious description that contains arbitrary HTML. When the node is selected, it will render the arbitrary HTML, potentially triggering stored XSS. This vulnerability is fixed in 1.2.3.