Fixing Amazon Cognito's "Username/client id combination not found" Error During Email Update Verification

Exploring Email Verification Issues in Amazon Cognito

Developers frequently encounter a dilemma when putting in place a user flow that permits email address changes in Amazon Cognito: maintaining security without sacrificing user experience. There could be security vulnerabilities associated with Cognito's default configuration, which allows email changes without instant verification. To combat this, in an attempt to achieve a balance between security and user continuity, the email field's "Keep original attribute value active when an update is pending" option can be enabled. This feature, which takes a reasonable approach to user management, lets users receive a verification code to their new email while still allowing them to log in with their old email address.

The "UserNotFoundException: Username/client id combination not found" issue, which appears when users try to validate their new email address, is one example of an unanticipated problem that might occasionally result from this well-intended functionality. This problem draws attention to a weakness in the smooth user experience that Cognito seeks to offer and poses concerns about the fundamental workings of the verification procedure. Furthermore, although users can log in with unverified emails in practice, the documentation implies that confirmed contact information is required for login using an email address or phone number as an alias. This adds another level of complication to the process of securely managing user identities in Cognito.

Comprehending the Email Verification Process in Amazon Cognito

With Amazon Cognito, developers can easily handle user identities and authentication in a scalable and secure manner. Making sure that email addresses—which are frequently utilized as key identities in applications—are validated is an essential part of preserving user security. It takes careful consideration of the user pool's settings to update and verify an email address in Amazon Cognito, especially when doing so without requiring the user to change their password. An important part of this procedure is the setting "Keep original attribute value active when an update is pending". By enabling the system to keep the old email address active until the new one is validated, it effectively blocks unwanted access while the verification process is underway. By using this method, users are prevented from easily changing their email address to one they do not own and accessing another person's account without first undergoing the necessary verification.

The problem occurs, though, when the user attempts to confirm their new email address and receives the error message "UserNotFoundException: Username/client id combination not found". There are a number of possible causes for this error, including a discrepancy in the username and client ID, problems configuring the user pool, or errors in the code that handles user characteristics. It will be necessary to go deeply into the details of the application's code that communicates with Amazon Cognito's API in order to resolve this issue. Furthermore, the anomaly brought to light by the option to log in using an unverified email address suggests that user pool settings may have been misunderstood or incorrectly configured. Developers are responsible for making sure that the Cognito user pool settings meet the security specifications of their application, which may include requiring verified contact information for authentication.

const AWS = require('aws-sdk');
const cognito = new AWS.CognitoIdentityServiceProvider({ region: 'us-east-1' });
const clientId = 'your_client_id_here'; // Replace with your Cognito Client ID
const username = 'user@example.com'; // The current username or email
const newEmail = 'newuser@example.com'; // The new email to update to
const verificationCode = '123456'; // The verification code sent to the new email

// Function to initiate the email update process
async function initiateEmailUpdate() {
  const params = {
    AccessToken: 'your_access_token_here', // Replace with the user's access token
    UserAttributes: [{
      Name: 'email',
      Value: newEmail
    }]
  };
  await cognito.updateUserAttributes(params).promise();
}

// Function to verify the new email with the verification code
async function verifyNewEmail() {
  const params = {
    ClientId: clientId,
    Username: username,
    ConfirmationCode: verificationCode,
    AttributeName: 'email'
  };
  await cognito.verifyUserAttribute(params).promise();
}

import boto3
cognito_client = boto3.client('cognito-idp', region_name='us-east-1')
client_id = 'your_client_id_here'  # Replace with your Cognito Client ID
username = 'user@example.com'  # The current username or email
new_email = 'newuser@example.com'  # The new email to update to
verification_code = '123456'  # The verification code sent to the new email

# Function to update user email
def initiate_email_update(access_token):
    response = cognito_client.update_user_attributes(
        AccessToken=access_token,
        UserAttributes=[{'Name': 'email', 'Value': new_email}]
    )
    return response

# Function to verify the new email with the verification code
def verify_new_email():
    response = cognito_client.verify_user_attribute(
        AccessToken='your_access_token_here',  # Replace with user's access token
        AttributeName='email',
        Code=verification_code
    )
    return response

Using Email Verification to Strengthen Security in Amazon Cognito

The challenge in integrating a successful email verification procedure in Amazon Cognito is striking a balance between security precautions and user convenience. This becomes more clear when people want to change their email addresses. Aiming to reduce the possibility of unwanted access while the update is being processed, Cognito's configuration parameter "Keep original attribute value active when an update is pending" This configuration maintains the integrity of the user's account by permitting constant access using the previous email address until the new one is validated. The problem arises, though, when this smooth transition is halted by errors like "UserNotFoundException," which can impede user productivity and cause security issues.

An additional layer of complexity to the problem is the apparent inconsistent enforcement of email verification for user sign-in, as noted in AWS literature. Practical observations show that utilizing an email address or phone number as an alias during sign-in does not require confirmed contact information, despite what the documentation claims. This inconsistency highlights the necessity for a thorough comprehension and application of Cognito's email verification functionalities and may give rise to possible security flaws. Developers are responsible for making sure that the authentication flow in their application is safe and easy to use, filling in any gaps that may be present in the documentation or the service's real behavior.