Lambda Function URL Without Authentication

What this rule checks

Detects Lambda Function URLs configured with AuthType NONE, which allows unauthenticated public invocation.

How to fix it

1. 1Set AuthType to AWS_IAM so callers are authorized with IAM SigV4
2. 2Or front the function with an authenticated API Gateway / CloudFront + WAF

import * as lambda from 'aws-cdk-lib/aws-lambda';

const fn = new lambda.Function(this, 'Fn', {
  runtime: lambda.Runtime.NODEJS_20_X,
  handler: 'index.handler',
  code: lambda.Code.fromInline('exports.handler = async () => {};'),
});
new lambda.CfnUrl(this, 'Url', {
  authType: 'NONE',
  targetFunctionArn: fn.functionArn,
});

import * as lambda from 'aws-cdk-lib/aws-lambda';

const fn = new lambda.Function(this, 'Fn', {
  runtime: lambda.Runtime.NODEJS_20_X,
  handler: 'index.handler',
  code: lambda.Code.fromInline('exports.handler = async () => {};'),
});
new lambda.CfnUrl(this, 'Url', {
  authType: 'AWS_IAM',
  targetFunctionArn: fn.functionArn,
});

CDK Insights pinpoints the exact file and line in your CDK source for every finding, so you can jump straight to the fix.

Affected resource types

Intentional? Suppress this finding

Sometimes a flag is deliberate — a genuinely public endpoint, say. You can dismiss lambda-url-auth-none and the reason is kept in the report, not silently hidden.

In .cdk-insights.json:

{
  "ignoreRules": [
    { "id": "lambda-url-auth-none", "reason": "Why this is intentional" }
  ]
}

Or inline in your CDK code:

Validations.of(scope).acknowledge({
  id: 'cdk-insights::lambda-url-auth-none',
  reason: 'Why this is intentional',
});

Use the rule ID lambda-url-auth-none shown above — not the CDK-* ID from SARIF / GitHub code scanning. To dismiss every finding on one construct instead, use ignorePaths. Suppression docs →

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