Lightweight Music Server (LMS) though 3.76.0 contains a stored cross-site scripting vulnerability that allows attackers to execute arbitrary JavaScript by embedding malicious HTML in media file metadata tags such as GENRE, ARTIST, or ALBUM. Attackers can introduce a crafted media file into the victim's library, causing the payload to be saved during library scanning and executed automatically in the web interface due to tag content being rendered using Wt::TextFormat::UnsafeXHTML without sanitization in src/lms/ui/Utils.cpp.