The Contact page in Monica 2.19.1 allows stored XSS via the Last Name field.
https://huntr.dev/bounties/2-other-monica/
https://github.com/monicahq/monica/pull/4543
https://github.com/monicahq/monica/issues/4888
http://packetstormsecurity.com/files/161501/Monica-2.19.1-Cross-Site-Scripting.html