Mendix Runtime allows for entity enumeration due to distinguishable responses in certain client actions. This could allow an unauthenticated remote attacker to list all valid entities and attribute names of a Mendix Runtime-based application.
Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens is preparing further fix versions and recommends countermeasures for products where fixes are not, or not yet available.

https://cert-portal.siemens.com/productcert/html/ssa-874353.html