In MISP before 2.4.193, menu_custom_right_link parameters can be set via the UI (i.e., without using the CLI) and thus attackers with admin privileges can conduct XSS attacks via a global menu link.
https://github.com/MISP/MISP/releases/tag/v2.4.193
https://github.com/MISP/MISP/commit/33a1eb66408e16a7535b2bae48303efd9501a26a