GHSA-QQ4X-C6H6-RFXH

The AWS Cloud Development Kit (CDK) is an open-source framework for defining cloud infrastructure using code. Customers use it to create their own applications which are converted to AWS CloudFormation templates during deployment to a customer’s AWS account. CDK contains pre-built components called "constructs" that are higher-level abstractions providing defaults and best practices. This approach enables developers to use familiar programming languages to define complex cloud infrastructure more efficiently than writing raw CloudFormation templates.

The CDK Cognito UserPool construct deploys an AWS cognito user pool. An Amazon Cognito user pool is a user directory for web and mobile app authentication and authorization. Customers can deploy a client under this user pool through construct ‘UserPoolClient’ or through helper method 'addClient'. A user pool client resource represents an Amazon Cognito user pool client which is a configuration within a user pool that interacts with one mobile or web application authenticating with Amazon Cognito.

When users of the 'cognito.UserPoolClient' construct generate a secret value for the application client in AWS CDK, they can then reference the generated secrets in their stack. The CDK had an issue where, when the custom resource performed an SDK API call to 'DescribeCognitoUserPoolClient' to retrieve the generated secret, the full response was logged in the associated lambda function's log group. Any user authenticated in the account where logs of the custom resource are accessible and who has read-only permission could view the secret written to those logs.

This issue does not affect customers who are generating the secret value outside of the CDK as the secret is not referenced or logged.

Workarounds

Users can override the implementation changing Logging to be Logging.withDataHidden(). For example define class CustomUserPoolClient extends UserPoolClient and  in the new class define get userPoolClientSecret() to use Logging.withDataHidden().

Example

export class CustomUserPoolClient extends UserPoolClient {

  private readonly customUserPool : UserPool;
  private readonly customuserPoolClientId : string;
  constructor(scope: Construct, id: string, props: UserPoolClientProps) {
    super(scope, id, props);

    this.customUserPool = new UserPool(this, 'pool', {
      removalPolicy: RemovalPolicy.DESTROY,
    });

    const client = this.customUserPool.addClient('client', { generateSecret: true });
  }



  // Override the userPoolClientSecret getter to always return the secret
  public get userPoolClientSecret(): SecretValue {
    // Create the Custom Resource that assists in resolving the User Pool Client secret
    const secretValue = SecretValue.resourceAttribute(new AwsCustomResource(
      this,
      'DescribeCognitoUserPoolClient',
      {
    resourceType: 'Custom::DescribeCognitoUserPoolClient',
    onUpdate: {
      region: cdk.Stack.of(this).region,
      service: 'CognitoIdentityServiceProvider',
      action: 'describeUserPoolClient',
      parameters: {
        UserPoolId: this.customUserPool.userPoolId,
        ClientId: this.customUserPool,
      },
      physicalResourceId: PhysicalResourceId.of(this.userPoolClientId),
      // Disable logging of sensitive data
      logging: Logging.withDataHidden(),
    },
    policy: AwsCustomResourcePolicy.fromSdkCalls({
      resources: [this.customUserPool.userPoolArn],
    }),
    installLatestAwsSdk: false,
      },
    ).getResponseField('UserPoolClient.ClientSecret'));
    
    return secretValue;
  }
}

References

If you have any questions or comments about this advisory please contact AWS/Amazon Security via our vulnerability reporting page or directly via email to [email protected]. Please do not create a public GitHub issue.

To leverage this issue, an actor has to be authenticated in the account where logs of the custom resource Custom::DescribeCognitoUserPoolClient are accessible and have read-only permission for lambda function logs.

Users can review access to their log group through AWS CloudTrail logs to detect any unexpected access to read the logs.

Impacted versions: >2.37.0 and <=2.187.0

GHSA-QQ4X-C6H6-RFXH has a CVSS score of 6.5 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.187.0); upgrading removes the vulnerable code path.

Kodem intelligence

The patches are included in the AWS CDK Library release v2.187.0. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes. To fully address this issue, users should rotate the secret by generating a new secret stored in AWS Secrets Manager. References to the secret will use the new secret on update.

When new CDK applications using the latest version are initialized, they will use the new behavior with updated logging.

Existing applications must upgrade to the latest version, change the feature flag (@aws-cdk/cognito:logUserPoolClientSecretValue) to false, redeploy the application to apply this fix and use the new implementation with updated logging behavior.

1. What is GHSA-QQ4X-C6H6-RFXH? GHSA-QQ4X-C6H6-RFXH is a medium-severity security vulnerability in aws-cdk-lib (npm), affecting versions >= 2.37.0, < 2.187.0. It is fixed in 2.187.0.
2. How severe is GHSA-QQ4X-C6H6-RFXH? GHSA-QQ4X-C6H6-RFXH has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of aws-cdk-lib are affected by GHSA-QQ4X-C6H6-RFXH? aws-cdk-lib (npm) versions >= 2.37.0, < 2.187.0 is affected.
4. Is there a fix for GHSA-QQ4X-C6H6-RFXH? Yes. GHSA-QQ4X-C6H6-RFXH is fixed in 2.187.0. Upgrade to this version or later.
5. Is GHSA-QQ4X-C6H6-RFXH exploitable, and should I be worried? Whether GHSA-QQ4X-C6H6-RFXH is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether GHSA-QQ4X-C6H6-RFXH is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix GHSA-QQ4X-C6H6-RFXH? Upgrade aws-cdk-lib to 2.187.0 or later.

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