Ultimate Member vulnerabilities

Authorization Bypass Through User-Controlled Key vulnerability in Ultimate Member Ultimate Member ultimate-member allows Privilege Escalation.This issue affects Ultimate Member: from n/a through 2.13.1.

The Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'form_id' parameter in all versions up to, and including, 2.13.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The injected payload is stored in the registering user's 'submitted' usermeta via update_user_meta() and is only triggered when an administrator opens the affected user record in the wp-admin Users modal, which inserts the unescaped output via jQuery .html().

The Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 2.13.1 This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for unauthenticated attackers to view privacy-restricted member profile field values — including fields explicitly configured as owner-only, members-only, or role-restricted — by querying the publicly accessible wp_ajax_nopriv_um_get_members endpoint. The nonce required by the endpoint ('um-frontend-nonce') is emitted to all unauthenticated visitors via wp_localize_script, meaning it provides no meaningful access control and any anonymous visitor can satisfy the endpoint's authentication requirements.

The Ultimate Member plugin for WordPress is vulnerable to Account Takeover via Password Reset Link Disclosure in all versions up to and including 2.11.4. This is 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.

The Ultimate Member plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 2.11.2. This is due to the '{usermeta:password_reset_link}' template tag being processed within post content via the '[um_loggedin]' shortcode, which generates a valid password reset token for the currently logged-in user viewing the page. This makes it possible for authenticated attackers, with Contributor-level access and above, to craft a malicious pending post that, when previewed by an Administrator, generates a password reset token for the Administrator and exfiltrates it to an attacker-controlled server, leading to full account takeover.