We have published security release 5.3.20 and 5.4.10 on GitHub, see https://github.com/ILIAS-eLearning/ILIAS/releases .

Important: These releases contain important security fixes and it is recommended to update your system.

Please have a look at the release notes for more information about these releases https://docu.ilias.de/goto_docu_lm_35.html .