The Otter WordPress plugin before 2.2.6 does not sanitize some user-controlled file paths before performing file operations on them. This leads to a PHAR deserialization vulnerability on PHP < 8.0 using the phar:// stream wrapper.
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.