Multiple Stored XSS vulnerabilities exist in Seafile Server version 13.0.15,13.0.16-pro,12.0.14 and prior and fixed in 13.0.17, 13.0.17-pro, and 12.0.20-pro, via the Seadoc (sdoc) editor. The application fails to properly sanitize WebSocket messages regarding document structure updates. This allows authenticated remote attackers to inject malicious JavaScript payloads via the src attribute of embedded Excalidraw whiteboards or the href attribute of anchor tags
https://manual.seafile.com/13.0/changelog/server-changelog/
https://manual.seafile.com/13.0/changelog/changelog-for-seafile-professional-server/
https://manual.seafile.com/12.0/changelog/changelog-for-seafile-professional-server/
https://github.com/haiwen/seahub/commit/4c5301747bdb84c64b2f2b3230417df2d1cc8987
https://github.com/haiwen/seadoc-editor/commit/8fa988aaede072b2ae073d1b2edcb2fc691423b2
https://gist.github.com/gabdevele/1b7e30ab367b26042fa32f45aa12ce2f