CVE-2026-75957

9.8 CRITICAL

Published 2026-10-01 · Updated 2026-10-01

AI risk analysis

Summary: The Ultimate Multisite plugin for WordPress allows unauthenticated attackers to bypass authentication and log in as any existing user, including Network Super Admins, by exploiting a flaw in the `checkout_form` parameter.
Exploitability: Exploitation requires knowledge of the targeted user's email address and a checkout nonce, making it moderately hard to exploit.
Blast radius: If exploited, this flaw could grant full access to any existing WordPress user account, potentially leading to complete compromise of the WordPress site or network.
Detection: No reliable host or network indicator is derivable from the published description.
Prioritized remediation: Disable the affected feature or upgrade to version 2.15.1 or later.

auth-bypasswebwp-plugin

Analysis generated locally by qwen2.5:7b-instruct (no data left the box). AI-assisted — verify against primary sources before acting.

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.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weaknesses

CWE-287

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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