MAXFAILEDLOGINATTEMPTS in ExtendedInformation can be saved as a string if set via WS. This is due to the fact that the information carrier over WS (ExtendedInformationWS) only saves Strings, so it gets saved as such as well.

This leads to the following error:

java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer
  at org.cesecore.certificates.endentity.ExtendedInformation.getMaxLoginAttempts(ExtendedInformation.java:223)

The trivial fix is to simply guard against a ClassCastException and instead produce the int from a String instead.