A cross-site scripting vulnerability exists in Citadel versions prior to 994. When a malicious user sends an instant message with some JavaScript code, the script may be executed on the web browser of the victim user.
https://www.citadel.org/download.html
https://jvn.jp/en/jp/JVN08237727/
https://code.citadel.org/citadel/citadel/-/commit/f0dac5ff074ad686fa71ea663c8ead107bd3041e