This vulnerability is described as an account takeover, however there were rumours early on that this may be more significant.
Assetnote released a research article on the 22nd of October breaking down the vulnerability, highlighting that this is far more serious than Adobe have described. Ultimately through the deserialization vulnerability, an attacker can gain code execution by the creation of a backdoor php file. In order to achieve that, the attacker must know, or be able to guess the (e.g. default) installation path of Magento.