OCTOBER 6, 2026
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Case File

CVE-2026-75957

CRITICAL · CVSS 9.8 EPSS 0.58% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-10-01 · Last synced 2026-10-06

CyberRota Analysis

AI-Generated

The Ultimate Multisite plugin for WordPress is vulnerable to an authentication bypass, allowing unauthenticated attackers to log in as any existing user, including Network Super Admins, by exploiting the `checkout_form` parameter in the `login_customer_after_checkout` function. This critical vulnerability arises from a flawed AJAX handler that permits access to sensitive functions without proper validation, making it imperative for all WordPress sites using this plugin to prioritize immediate updates to version 2.15.1 or later. Organizations, particularly those with elevated user roles or sensitive data, should take swift action to mitigate the risk of unauthorized access.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
exploit

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CVE
CVE-2026-75957
Severity
CRITICAL
CVSS
9.8
EPSS
0.58%
WordPress

Original NVD 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.