Language: TypeScript
Label: vulnerable
CWE: CWE-331 \u2014 Insufficient Entropy
The product uses an algorithm or scheme that produces insufficient entropy, leaving patterns or clusters of values that are more likely to occur than others.

Code:
  async encryptString(key, plaintext) {
    const abIv = crypto.getRandomValues(new Uint8Array(16));

    const abPlaintext = Buffer.from(plaintext).buffer;
    const abPayload = await crypto.subtle.encrypt({ name: 'AES-CBC', iv: abIv }, key, abPlaintext);

    const ciphertext = concatArrayBuffer(abIv.buffer, abPayload);

    return Buffer.from(ciphertext).toString('utf8');
  }