VPC Default Security Group Has Rules

What this rule checks

Detects default VPC security groups with ingress or egress rules; defaults should be empty.

How to fix it

1. 1Remove all rules from the default security group
2. 2Use purpose-built security groups instead

import { App, Stack } from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as ec2 from 'aws-cdk-lib/aws-ec2';

// FLAGGED: rules added to the VPC's default security group.
new ec2.CfnSecurityGroup(this, 'DefaultSg', {
  groupName: 'default',
  groupDescription: 'default VPC security group',
  securityGroupIngress: [
    { ipProtocol: 'tcp', fromPort: 443, toPort: 443, cidrIp: '0.0.0.0/0' },
  ],
});

import { App, Stack } from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as ec2 from 'aws-cdk-lib/aws-ec2';

// FIXED: default group left empty; a purpose-built SG carries the rules.
new ec2.CfnSecurityGroup(this, 'DefaultSg', {
  groupName: 'default',
  groupDescription: 'default VPC security group',
});
new ec2.CfnSecurityGroup(this, 'WebSg', {
  groupDescription: 'web tier',
  securityGroupIngress: [
    { ipProtocol: 'tcp', fromPort: 443, toPort: 443, cidrIp: '0.0.0.0/0' },
  ],
});

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 vpc-default-security-group-rules-present and the reason is kept in the report, not silently hidden.

In .cdk-insights.json:

{
  "ignoreRules": [
    { "id": "vpc-default-security-group-rules-present", "reason": "Why this is intentional" }
  ]
}

Or inline in your CDK code:

Validations.of(scope).acknowledge({
  id: 'cdk-insights::vpc-default-security-group-rules-present',
  reason: 'Why this is intentional',
});

Use the rule ID vpc-default-security-group-rules-present 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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