The Mapster WP Maps plugin for WordPress is vulnerable to Arbitrary User Meta Write in all versions up to, and including, 1.23.0 via the myprofileupdate() function. This is due to the function performing no nonce verification, no capability check, and no allowlist validation on the meta key supplied via the acf-photo-gallery-groups POST parameter before passing both the meta key and its corresponding value directly to updateusermeta(). This makes it possible for authenticated attackers, with Subscriber-level access and above, to update arbitrary user meta values, though privilege escalation is not possible.