Ultimate Member < 2.12.0 - Contributor+ Account Takeover via Password Reset Link Disclosure

Description

The plugin is vulnerable to Account Takeover via Password Reset Link Disclosure due to a chain of three logic bugs: (1) an MD5 hash fallback in get_directory_by_hash() that allows any post to be used as a member directory by computing SUBSTRING(MD5(post_id), 11, 5), (2) a strstr() parsing logic flaw in post_data() that allows bypassing WordPress's protected meta key restrictions by placing '_um_' anywhere in the meta key name rather than at the start, and (3) missing field name validation in build_user_card_data() that allows arbitrary field names including 'password_reset_link' to be passed to um_filtered_value(). This makes it possible for authenticated attackers with Contributor-level access and above to create a malicious post via XMLRPC with crafted meta fields, use the MD5 fallback to point the member directory AJAX handler to their post, inject 'password_reset_link' into the tagline_fields configuration, and leak live password reset URLs for all users in the member directory response, including administrators.