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 decryptArrayBuffer(key, ciphertext) {
    const abIv = ciphertext.slice(0, 16);

    return crypto.subtle.decrypt({ name: 'AES-CBC', iv: abIv }, key, ciphertext.slice(16));
  }