{"schema":"threatline.record/2","record":{"id":"CVE-2026-75957","aliases":[],"summary":"Ultimate Multisite <= 2.15.0 - Unauthenticated Authentication Bypass via 'checkout_form' Parameter","details":"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.","categories":["Applications & CMS"],"product":"Ultimate Multisite – WordPress Multisite SaaS & WaaS Platform","vendor":"superdav42","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-75957","source_modified_at":"2026-10-01T13:42:37.093Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"Ultimate Multisite – WordPress Multisite SaaS & WaaS Platform","vendor":"superdav42","versions":[{"version":"0","status":"affected","lessThanOrEqual":"2.15.0","versionType":"semver"}],"defaultStatus":"unaffected"}],"fixed_versions":[],"cvss":9.8,"severity":"Critical","kev":{"listed":false},"epss":{"probability":0.00576,"percentile":0.46798,"score_date":"2026-10-23"},"published_at":"2026-10-01T07:40:23.541Z","modified_at":"2026-10-01T13:42:37.093Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-75957","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-10-01T13:42:37.093Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-75957","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://www.wordfence.com/threat-intel/vulnerabilities/id/66cb8c6f-d405-4115-a626-040e9b5b1e62?source=cve"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.15.0/inc/checkout/class-checkout.php#L2489"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.15.0/inc/checkout/class-checkout.php#L1223"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.15.0/inc/checkout/class-checkout.php#L2700"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.15.0/inc/models/class-checkout-form.php#L1352"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.15.0/inc/checkout/class-checkout.php#L208"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.14.2/inc/checkout/class-checkout.php#L2489"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.14.2/inc/checkout/class-checkout.php#L1223"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.14.2/inc/checkout/class-checkout.php#L2700"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.14.2/inc/models/class-checkout-form.php#L1352"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/browser/ultimate-multisite/tags/2.14.2/inc/checkout/class-checkout.php#L208"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/changeset?reponame=&new=3653623%40ultimate-multisite%2Ftags%2F2.15.1&old=3634394%40ultimate-multisite%2Ftags%2F2.15.0"},{"source":"CVE List","url":"https://plugins.trac.wordpress.org/changeset/3653622/ultimate-multisite/trunk/inc/checkout/class-checkout.php"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"yes","technical_impact":"total","assessed_at":"2026-10-01T13:40:29.024281Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-01T13:42:37.093Z","content_hash":"a2bdf4d310018c24821b7e64f8846fe076b64bb6605be54f37b5ec7449f95421"}}