EUVD Vulnerability Catalog

EUVD-2026-90546

Severity: CRITICAL Base Score: 9.8 CVSS Version: 3.1

Vulnerability Description

The Ultimate Multisite – WordPress Multisite SaaS & WaaS Platform plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 2.15.0 via the `checkout_form` parameter of the `login_customer_after_checkout` function. This is due to the publicly accessible `wu_ajax_nopriv_wu_validate_form` AJAX handler accepting a freely obtainable checkout nonce, and the `checkout_form=wu-finish-checkout` parameter causing `get_validation_rules()` to discard all validation rules while `finish_checkout_form_fields()` returns an empty step list — forcing `is_last_step()` to return true and routing the request directly into full order processing — after which `maybe_create_customer()` resolves the attacker-supplied `email_address` to an existing WordPress user ID without any authentication or ownership verification, and `login_customer_after_checkout()` calls `wp_set_auth_cookie()` for that user ID via a passwordless code path. This makes it possible for unauthenticated attackers to log in as any existing WordPress user — including a Network Super Admin — simply by knowing their email address. Exploitation requires that the targeted user account has no pre-existing Ultimate Multisite customer record; accounts such as a Network Super Admin on a fresh Multisite install, or any administrator or editor added before Ultimate Multisite was configured, satisfy this condition and are therefore exploitable.

CVSS Vector Analysis

Below is the complete, human-readable breakdown of the CVSS metric string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

▪ Attack Vector (AV): Network
▪ Attack Complexity (AC): Low
▪ Privileges Required (PR): None
▪ User Interaction (UI): None
▪ Scope (S): Unchanged
▪ Confidentiality Impact (C): High
▪ Integrity Impact (I): High
▪ Availability Impact (A): High

Affected Vendors & Systems

Vendor superdav42

References & Advisory Links

Metadata Profile

Database Authority

European Union Agency for Cybersecurity (ENISA) EUVD

Assigner

Wordfence

EPSS Probability

0

Known Aliases
CVE-2026-75957
Published On

2026-10-01

Last Updated

2026-10-01