Session tokens are cryptographically random and at least 128 bits

Session tokens, password reset links, and email verification codes generated with Math.random() or Date.now() are predictable. CWE-338 (Use of Cryptographically Weak PRNG) and CWE-330 (Use of Insufficiently Random Values) describe how an attacker who knows the approximate generation time can enumerate the token space in seconds, enabling account takeover without ever knowing the victim's password. OWASP A02 (Cryptographic Failures) and NIST 800-53 SC-8 both require cryptographically secure randomness for security tokens. Six-digit numeric email codes have only one million possibilities — brute-forceable in under a minute against a rate-unlimited endpoint.

Use crypto.randomBytes or crypto.randomUUID() for every security-sensitive token. Store reset tokens hashed (SHA-256), send the plaintext to the user:

import crypto from 'crypto'

const rawToken = crypto.randomBytes(32).toString('hex')  // 256 bits
const storedToken = crypto.createHash('sha256').update(rawToken).digest('hex')

await db.passwordReset.create({
  data: { token: storedToken, userId, expiresAt: new Date(Date.now() + 3_600_000) },
})
// Email rawToken to the user, never storedToken

UUID v4 (crypto.randomUUID()) is acceptable for session identifiers — 122 bits of randomness.