CVE-2016-7798

The openssl gem for Ruby uses the same initialization vector (IV) in GCM Mode (aes-*-gcm) when the IV is set before the key, which makes it easier for context-dependent attackers to bypass the encryption protection mechanism.

Mitigation

A possible workaround to this flaw is, when using aes-256-gcm mode, always set the key first and then the iv. For example when setting random keys and iv use the following code segment:

key = cipher.random_key
iv = cipher.random_iv