CVE-2026-83628

The Theme My Login plugin for WordPress is vulnerable to Missing Authorization in versions up to, and including, 7.1.15 on Multisite installations. This is due to the tml_ms_signup_handler() function's gimmeanotherblog branch failing to enforce the network's active_signup registration policy, checking only is_user_logged_in() while sibling branches such as validate-blog-signup apply the full policy gate. This makes it possible for authenticated attackers, with Subscriber-level access and above, to directly POST stage=gimmeanotherblog to Theme My Login's signup route, bypassing the configured registration policy entirely — even when it is set to none or user — which causes wpmu_create_blog() to execute with the attacker's user ID, after which WordPress core assigns the Administrator role on the newly created subsite via add_user_to_blog(). The privilege gain is scoped to the newly created subsite only; the attacker's account retains Subscriber-level access on the main site and does not obtain Super Admin or network-level capabilities such as manage_network or manage_sites.