{"id":"CVE-2026-103646","state":"PUBLISHED","title":"Ultimate Multisite < 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.","publishedAt":"2026-10-08T06:00:05.353Z","updatedAt":"2026-10-08T10:59:19.784Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"CISA-ADP"},"assigner":"WPScan","products":["Unknown Ultimate Multisite"],"affected":[{"vendor":"Unknown","product":"Ultimate Multisite","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"2.17.0","versionType":"semver"}]}],"references":["https://wpscan.com/vulnerability/a05da0ad-5d92-406f-b182-b3ed1f8389f3/"],"weaknesses":["CWE-287"],"ingestedAt":"2026-10-29T20:10:23.711Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/103xxx/CVE-2026-103646.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-103646","state":"PUBLISHED","datePublished":"2026-10-08T06:00:05.353Z","dateUpdated":"2026-10-08T10:59:19.784Z","assignerShortName":"WPScan","assignerOrgId":"1bfdd5d7-9bf6-4a53-96ea-42e2716d7a81","dateReserved":"2026-10-01T06:42:15.491Z"},"containers":{"cna":{"title":"Ultimate Multisite < 2.17.0 - Unauthenticated Authentication Bypass via 'email_address' Parameter","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Unknown","product":"Ultimate Multisite","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"2.17.0","versionType":"semver"}]}],"references":[{"url":"https://wpscan.com/vulnerability/a05da0ad-5d92-406f-b182-b3ed1f8389f3/","tags":["exploit","vdb-entry","technical-description"]}],"problemTypes":[{"descriptions":[{"description":"CWE-287 Improper Authentication","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"WPScan","orgId":"1bfdd5d7-9bf6-4a53-96ea-42e2716d7a81","dateUpdated":"2026-10-08T06:00:05.353Z"},"credits":[{"lang":"en","value":"Erwan LR (WPScan)","type":"finder"},{"lang":"en","value":"WPScan","type":"coordinator"}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"WPScan CVE Generator"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":9.8,"attackVector":"NETWORK","baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","integrityImpact":"HIGH","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"HIGH"}},{"other":{"type":"ssvc","content":{"id":"CVE-2026-103646","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-08T10:58:10.240709Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-287","lang":"en","type":"CWE","description":"CWE-287 Improper Authentication"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-08T10:59:19.784Z"}}]}}}