Login error after automatic upgrade to 4.4.1

I have wordpress installed in a directory called /wp, but the main site sits in the parent domain directory (domain.com as opposed to domain.com/wp). Since the automatic upgrade to WordPress 4.4.1, going to domain.com/wp/wp-login.php produces a captcha page, which has never been on the login before. Once I enter the captcha value, I can taken to a 404 page located at domain.com/wp/wp/wp-login.php.

Is there any reason why it’s adding the extra /wp? I didn’t change anything on the backend before or after the automatic upgrade, and this has never happened before. Any ideas? I’d really appreciate any help.