{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-75957","assignerOrgId":"b15e7b5b-3da4-40ae-a43c-f7aa60e62599","state":"PUBLISHED","assignerShortName":"Wordfence","dateReserved":"2026-08-18T16:14:24.893Z","datePublished":"2026-10-01T07:40:23.541Z","dateUpdated":"2026-10-01T13:42:37.093Z"},"containers":{"cna":{"providerMetadata":{"orgId":"b15e7b5b-3da4-40ae-a43c-f7aa60e62599","shortName":"Wordfence","dateUpdated":"2026-10-01T07:40:23.541Z"},"affected":[{"vendor":"superdav42","product":"Ultimate Multisite – WordPress Multisite SaaS & WaaS Platform","versions":[{"version":"0","status":"affected","lessThanOrEqual":"2.15.0","versionType":"semver"}],"defaultStatus":"unaffected"}],"descriptions":[{"lang":"en","value":"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."}],"title":"Ultimate Multisite <= 2.15.0 - Unauthenticated Authentication Bypass via 'checkout_form' Parameter","references":[{"url":"https://www.wordfence.com/threat-intel/vulnerabilities/id/66cb8c6f-d405-4115-a626-040e9b5b1e62?source=cve"},{"url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.15.0/inc/checkout/class-checkout.php#L2489"},{"url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.15.0/inc/checkout/class-checkout.php#L1223"},{"url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.15.0/inc/checkout/class-checkout.php#L2700"},{"url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.15.0/inc/models/class-checkout-form.php#L1352"},{"url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.15.0/inc/checkout/class-checkout.php#L208"},{"url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.14.2/inc/checkout/class-checkout.php#L2489"},{"url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.14.2/inc/checkout/class-checkout.php#L1223"},{"url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.14.2/inc/checkout/class-checkout.php#L2700"},{"url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.14.2/inc/models/class-checkout-form.php#L1352"},{"url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.14.2/inc/checkout/class-checkout.php#L208"},{"url":"https://plugins.trac.wordpress.org/changeset?reponame=&new=3653623%40ultimate-multisite%2Ftags%2F2.15.1&old=3634394%40ultimate-multisite%2Ftags%2F2.15.0"},{"url":"https://plugins.trac.wordpress.org/changeset/3653622/ultimate-multisite/trunk/inc/checkout/class-checkout.php"}],"problemTypes":[{"descriptions":[{"lang":"en","description":"CWE-287 Improper Authentication","cweId":"CWE-287","type":"CWE"}]}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"}}],"credits":[{"lang":"en","type":"finder","value":"zickzick2"}],"timeline":[{"time":"2026-08-18T20:33:59.000Z","lang":"en","value":"Vendor Notified"},{"time":"2026-09-30T19:18:17.000Z","lang":"en","value":"Disclosed"}]},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-01T13:40:29.024281Z","id":"CVE-2026-75957","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-10-01T13:42:37.093Z"}}]}}