Security Group Unrestricted Ingress

What this rule checks

Detects security groups with unrestricted ingress (0.0.0.0/0).

How to fix it

1. 1Restrict ingress to specific IP ranges
2. 2Use security group references for internal traffic
3. 3Implement least privilege network access

import * as ec2 from 'aws-cdk-lib/aws-ec2';

const vpc = new ec2.Vpc(this, 'Vpc', {
  maxAzs: 2,
  natGateways: 0,
  subnetConfiguration: [
    { name: 'isolated', subnetType: ec2.SubnetType.PRIVATE_ISOLATED, cidrMask: 24 },
  ],
});
const sg = new ec2.SecurityGroup(this, 'Sg', { vpc });
// SSH open to the whole internet.
sg.addIngressRule(ec2.Peer.anyIpv4(), ec2.Port.tcp(22), 'ssh');

import * as ec2 from 'aws-cdk-lib/aws-ec2';

const vpc = new ec2.Vpc(this, 'Vpc', {
  maxAzs: 2,
  natGateways: 0,
  subnetConfiguration: [
    { name: 'isolated', subnetType: ec2.SubnetType.PRIVATE_ISOLATED, cidrMask: 24 },
  ],
});
// allowAllOutbound:false keeps egress off 0.0.0.0/0; a single narrow
// ingress rule (private CIDR, HTTPS) is the only opening.
const sg = new ec2.SecurityGroup(this, 'Sg', {
  vpc,
  allowAllOutbound: false,
});
sg.addIngressRule(ec2.Peer.ipv4('10.0.0.0/16'), ec2.Port.tcp(443), 'internal https');

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 security-group-unrestricted-ingress and the reason is kept in the report, not silently hidden.

In .cdk-insights.json:

{
  "ignoreRules": [
    { "id": "security-group-unrestricted-ingress", "reason": "Why this is intentional" }
  ]
}

Or inline in your CDK code:

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

Use the rule ID security-group-unrestricted-ingress 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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