Concrete CMS (formerly concrete5) below 8.5.10 and between 9.0.0 and 9.1.2 did not use strict comparison for the legacy_salt so that limited authentication bypass could occur if using this functionality. Remediate by updating to Concrete CMS 9.1.3+ or 8.5.10+.
https://www.concretecms.org/about/project-news/security/concrete-cms-security-advisory-2022-10-31
https://github.com/concretecms/concretecms/releases/9.1.3
https://github.com/concretecms/concretecms/releases/8.5.10
https://documentation.concretecms.org/developers/introduction/version-history/913-release-notes
https://documentation.concretecms.org/developers/introduction/version-history/8510-release-notes