{"id":"CVE-2026-103646","aliases":["EUVD-2026-94761","GHSA-3qw6-7g4w-jh2g"],"status":"published","title":"Ultimate Multisite \u003c 2.17.0 - Unauthenticated Authentication Bypass via 'email_address' Parameter","description":"The Ultimate Multisite  WordPress plugin before 2.17.0 does not require authentication before a logged-out checkout is linked to, and logged in as, an existing WordPress account matching the submitted email address, and its duplicate-account check normalizes that address differently from the lookup used to create the customer, so an unauthenticated attacker can log in as any existing user, including a Network Super Admin, whose email address they know.\nThis bypass is not addressed by the 2.15.1 fix for CVE-2026-75957 and remains exploitable in all versions up to and including 2.16.1, the releases that fix was expected to cover. Exploitation requires a checkout form configured without a password field (auto-generated password) and a target account that has no existing customer record in the Ultimate Multisite  WordPress plugin before 2.17.0.","severity":{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"adp","from":"cve"},"epss":{"day":"2026-11-11","score":0.00357,"percentile":0.29839,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-287"],"published":"2026-10-08T06:00:05Z","modified":"2026-10-08T20:51:18Z","products":[{"vendor":"unknown","product":"ultimate multisite"}],"references":[{"url":"https://wpscan.com/vulnerability/a05da0ad-5d92-406f-b182-b3ed1f8389f3/","tags":["exploit","vdb-entry","technical-description"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-103646"},{"url":"https://wpscan.com/vulnerability/a05da0ad-5d92-406f-b182-b3ed1f8389f3"},{"url":"https://github.com/advisories/GHSA-3qw6-7g4w-jh2g"}],"sources":{"cve":[{"id":"CVE-2026-103646","title":"Ultimate Multisite \u003c 2.17.0 - Unauthenticated Authentication Bypass via 'email_address' Parameter","description":"The Ultimate Multisite  WordPress plugin before 2.17.0 does not require authentication before a logged-out checkout is linked to, and logged in as, an existing WordPress account matching the submitted email address, and its duplicate-account check normalizes that address differently from the lookup used to create the customer, so an unauthenticated attacker can log in as any existing user, including a Network Super Admin, whose email address they know.\nThis bypass is not addressed by the 2.15.1 fix for CVE-2026-75957 and remains exploitable in all versions up to and including 2.16.1, the releases that fix was expected to cover. Exploitation requires a checkout form configured without a password field (auto-generated password) and a target account that has no existing customer record in the Ultimate Multisite  WordPress plugin before 2.17.0.","status":"published","published":"2026-10-08T06:00:05.353Z","modified":"2026-10-08T10:59:19.784Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"adp"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T13:34:37.420074Z"}],"euvd":[{"id":"EUVD-2026-94761","description":"The Ultimate Multisite  WordPress plugin before 2.17.0 does not require authentication before a logged-out checkout is linked to, and logged in as, an existing WordPress account matching the submitted email address, and its duplicate-account check normalizes that address differently from the lookup used to create the customer, so an unauthenticated attacker can log in as any existing user, including a Network Super Admin, whose email address they know.\nThis bypass is not addressed by the 2.15.1 fix for CVE-2026-75957 and remains exploitable in all versions up to and including 2.16.1, the releases that fix was expected to cover. Exploitation requires a checkout form configured without a password field (auto-generated password) and a target account that has no existing customer record in the Ultimate Multisite  WordPress plugin before 2.17.0.","status":"published","published":"2026-10-08T06:00:05Z","modified":"2026-10-08T10:59:19Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T17:27:33.098422Z"}],"ghsa":[{"id":"GHSA-3qw6-7g4w-jh2g","title":"The Ultimate Multisite  WordPress plugin before 2.17.0 does not require authentication before a...","description":"The Ultimate Multisite  WordPress plugin before 2.17.0 does not require authentication before a logged-out checkout is linked to, and logged in as, an existing WordPress account matching the submitted email address, and its duplicate-account check normalizes that address differently from the lookup used to create the customer, so an unauthenticated attacker can log in as any existing user, including a Network Super Admin, whose email address they know.\nThis bypass is not addressed by the 2.15.1 fix for CVE-2026-75957 and remains exploitable in all versions up to and including 2.16.1, the releases that fix was expected to cover. Exploitation requires a checkout form configured without a password field (auto-generated password) and a target account that has no existing customer record in the Ultimate Multisite  WordPress plugin before 2.17.0.","status":"published","published":"2026-10-08T06:31:19Z","modified":"2026-10-08T12:34:23Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T15:12:56.476072Z"}],"nvd":[{"id":"CVE-2026-103646","description":"The Ultimate Multisite  WordPress plugin before 2.17.0 does not require authentication before a logged-out checkout is linked to, and logged in as, an existing WordPress account matching the submitted email address, and its duplicate-account check normalizes that address differently from the lookup used to create the customer, so an unauthenticated attacker can log in as any existing user, including a Network Super Admin, whose email address they know.\nThis bypass is not addressed by the 2.15.1 fix for CVE-2026-75957 and remains exploitable in all versions up to and including 2.16.1, the releases that fix was expected to cover. Exploitation requires a checkout form configured without a password field (auto-generated password) and a target account that has no existing customer record in the Ultimate Multisite  WordPress plugin before 2.17.0.","status":"published","published":"2026-10-08T06:16:37.957Z","modified":"2026-10-08T20:51:18.123Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"secondary"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T14:12:55.142936Z"}]}}