User Passwords Not Working After Bulk Importing Users with MD4 Algorithm Specified

After importing users with passwords hashed with MD4, users are not able to log in with their existing password.

• Invalid username or password errors observed by users despite valid credentials being provided.
• To reproduce this issue, bulk import one or more users with the custom_password_hash algorithm set to md4 and a valid MD4 hashed password included. For example:

{
  "email": "name@domain.com",
  "email_verified": false,
  "custom_password_hash": {
        "algorithm": "md4",
        "hash": {
              "value": "OGZiZDdjNTQ1Nzk4Yzk3OGM1ZDk0MTRmMmQ5MzBkMzg=",
               "encoding": "base64"
         }
     }
  }
]

• • Once imported, try to log in with the plaintext password. The login will be denied despite the credentials being correct.

• Password
• Bulk IMport
• MD4 Algorithm

This is often caused by the wrong encoding being set. For example, setting custom_password_hash.hash.encoding to base64 when the hash value is hex-encoded.

Make sure that the appropriate hash encoding value is used. This can be tested by hashing and encoding a known password of an existing user and comparing it to the existing hashed password.