The Gutenberg Template Library & Redux Framework plugin <= 4.2.11 for WordPress registered several AJAX actions available to unauthenticated users in the `includes` function in `redux-core/class-redux-core.php` that were unique to a given site but deterministic and predictable given that they were based on an md5 hash of the site URL with a known salt value of '-redux' and an md5 hash of the previous hash with a known salt value of '-support'. These AJAX actions could be used to retrieve a list of active plugins and their versions, the site's PHP version, and an unsalted md5 hash of site’s `AUTH_KEY` concatenated with the `SECURE_AUTH_KEY`.

A CWE-760: Use of a One-Way Hash with a Predictable Salt vulnerability exists in Modicon M221 (all references, all versions), that could allow an attacker to pre-compute the hash value using dictionary attack technique such as rainbow tables, effectively disabling the protection that an unpredictable salt would provide.