Joplin is an open source note-taking and to-do application that organises notes and lists into notebooks. Prior to 3.7.13, when Joplin Desktop is running with the opt-in Web Clipper server enabled, the server in packages/lib/ClipperServer.ts sends Access-Control-Allow-Origin: and allows an arbitrary website to call POST /auth and GET /auth/check because the pairing endpoints do not reject HTTP or HTTPS origins. The desktop confirmation dialog does not identify the requesting origin, so a victim who approves the generic prompt authorizes the attacking page, which then receives the permanent API token. The token provides ongoing read and write access to notes, folders, tags, resources, and master keys. This issue is fixed in version 3.7.13.