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CVE-2026-75957.

Source-reported disclosure and enrichment record.

SEVERITY / CVSSCRITICAL / 9.8CVSS 3.1 · security@wordfence.com
EXPLOITATION STATUSNot listed in the cached KEV catalogThis does not establish absence of exploitation.
RECORD STATUSDeferredModified Oct 01, 2026

Disclosure summary

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.

Source-reported weakness categories

CWE-287

Source-specific records & product guidance

Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.

NIST National Vulnerability Database · NVD-CVE-2026-75957

Open original source · Updated Oct 01, 2026

Only CPE matches marked vulnerable=true are indexed. AND/OR platform conditions must be checked in the original NVD record.

Original records & references

PUBLISHED 2026-10-01T04:16:52-04:00
MODIFIED 2026-10-01T10:17:30-04:00
INGESTED 2026-10-06T11:45:14-04:00