Issue Summary

We are experiencing an authentication issue with the ActiveDirectoryMembershipProvider class in a .NET Framework 4.0 application when users attempt to authenticate using passwords that are 32 characters or longer.

Environment Details

Application Framework: .NET Framework 4.0

Namespace: System.Web.Security

Assembly: System.Web.dll

Membership Provider: ActiveDirectoryMembershipProvider

Authentication Method: LDAP connection with Azure Active Directory integration

Method Used: Membership.Provider.ValidateUser(username, password)

Problem Description

The application successfully authenticates users with passwords shorter than 32 characters. However, authentication fails when the password length is 32 characters or more.

We have conducted the following tests:

32-character password without spaces or special characters: Authentication failed

12-character password with spaces but no special characters: Authentication succeeded

20-character password with special characters but no spaces: Authentication succeeded

Based on these tests, the issue appears to be related specifically to password length rather than spaces or special characters.

Does the ActiveDirectoryMembershipProvider in .NET Framework 4.0 support authentication with passwords that are 32 characters or longer?

Are there any known limitations, bugs, or configuration requirements related to password length when using ActiveDirectoryMembershipProvider with LDAP/Azure Active Directory?

Is there any specific configuration or workaround recommended by Microsoft to enable successful authentication with 32+ character passwords?

We would appreciate your guidance and any relevant Microsoft documentation regarding this behavior.