On the DotDev.co site Eric Barnes has written up a post talking about a recently announced vulnerability (and 0-day exploit) for WordPress allowing for password reset emails to be delivered to a user-specified address instead of the correct one on the account:

On the Exploitbox site Dawid Golunski shares a 0 day vulnerability in the WordPress core affecting all versions:

The vulnerability stems from WordPress using untrusted data by default when creating a password reset e-mail that is supposed to be delivered only to the e-mail associated with the owner’s account.

The post includes a snippet of code from the WordPress core where the issue lies, relying on the value from PHP's $_SERVER['SERVER_NAME'] variable for the domain in the address the reset email is sent to. Unfortunately this value is pulled from the Host header in the request and is user-controllable. There's a solution offered using an Apache setting and it's noted that this exploit only seems to work against the default VirtualHost as it will act as a fallback if the Host does not reference a configured domain.