Otter - Gutenberg Blocks <= 2.2.5 - Authenticated (Author+) PHAR Deserialization

The Otter - Gutenberg Blocks plugin for WordPress is vulnerable to deserialization of untrusted input via the 'fallback' parameter in versions up to, and including 1.2.7. This makes it possible for authenticated attackers with author privileges to call files using a PHAR wrapper that will deserialize and call arbitrary PHP Objects that can be used to perform a variety of malicious actions granted a POP chain is also present. It also requires that the attacker is successful in uploading a file with the serialized payload.