Avo is a framework to create admin panels for Ruby on Rails apps. A stored cross-site scripting (XSS) vulnerability was found in the key_value field of Avo v3.2.3 and v2.46.0. This vulnerability could allow an attacker to execute arbitrary JavaScript code in the victim's browser. The value of the key_value is inserted directly into the HTML code. In the current version of Avo (possibly also older versions), the value is not properly sanitized before it is inserted into the HTML code. This vulnerability could be used to steal sensitive information from victims that could be used to hijack victims' accounts or redirect them to malicious websites. Avo 3.2.4 and 2.47.0 include a fix for this issue. Users are advised to upgrade.