Roundcube before 1.4.14, 1.5.x before 1.5.4, and 1.6.x before 1.6.3 allows XSS via text/plain e-mail messages with crafted links because of program/lib/Roundcube/rcube_string_replacer.php behavior.
https://www.hivepro.com/threat-advisory/roundcube-webmail-faces-unrelenting-exploitation/
https://thecyberthrone.in/2024/02/13/cisa-adds-roundcube-webmail-cve-2023-43770-to-its-kev-catalog/
https://roundcube.net/news/2023/09/15/security-update-1.6.3-released
https://lists.debian.org/debian-lts-announce/2023/09/msg00024.html
https://github.com/roundcube/roundcubemail/commit/e92ec206a886461245e1672d8530cc93c618a49b