Contao is an Open Source CMS. In versions starting from 4.9.14 and prior to 4.13.56, 5.3.38, and 5.6.1, protected content elements that are rendered as fragments are indexed and become publicly available in the front end search. This issue has been patched in versions 4.13.56, 5.3.38, and 5.6.1. A workaround involves disabling the front end search.
https://github.com/contao/contao/security/advisories/GHSA-2xmj-8wmq-7475
https://github.com/contao/contao/commit/a03976c459b6f3985a28f6488b82a76ffb6c0514
https://contao.org/en/security-advisories/information-disclosure-in-the-front-end-search-index