IAM Cross-Account Trust

What this rule checks

Detects IAM roles with cross-account trust relationships.

How to fix it

1. 1Verify cross-account trust is intentional
2. 2Add conditions to restrict access (e.g., external ID)
3. 3Document the business justification

import { Role, ArnPrincipal } from 'aws-cdk-lib/aws-iam';

new Role(this, 'PartnerAccessRole', {
  assumedBy: new ArnPrincipal('arn:aws:iam::111122223333:root'),
});

import { Role, ServicePrincipal } from 'aws-cdk-lib/aws-iam';

new Role(this, 'PartnerAccessRole', {
  assumedBy: new ServicePrincipal('lambda.amazonaws.com'),
});

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 iam-cross-account-trust and the reason is kept in the report, not silently hidden.

In .cdk-insights.json:

{
  "ignoreRules": [
    { "id": "iam-cross-account-trust", "reason": "Why this is intentional" }
  ]
}

Or inline in your CDK code:

Validations.of(scope).acknowledge({
  id: 'cdk-insights::iam-cross-account-trust',
  reason: 'Why this is intentional',
});

Use the rule ID iam-cross-account-trust 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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