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.
This 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.
Metrics
Affected Vendors & Products
References
History
Fri, 09 Oct 2026 09:15:00 +0000
| Type | Values Removed | Values Added |
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| First Time appeared |
Wordpress-extensions
Wordpress-extensions ultimate Multisite |
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| Vendors & Products |
Wordpress-extensions
Wordpress-extensions ultimate Multisite |
Thu, 08 Oct 2026 11:30:00 +0000
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|---|---|---|
| Metrics |
cvssV3_1
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Thu, 08 Oct 2026 08:00:00 +0000
| Type | Values Removed | Values Added |
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| Weaknesses | CWE-287 |
Thu, 08 Oct 2026 06:15:00 +0000
| Type | Values Removed | Values Added |
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| 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. This 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. | |
| Title | Ultimate Multisite < 2.17.0 - Unauthenticated Authentication Bypass via 'email_address' Parameter | |
| References |
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Status: PUBLISHED
Assigner: WPScan
Published: 2026-10-08T06:00:05.353Z
Updated: 2026-10-08T10:59:19.784Z
Reserved: 2026-10-01T06:42:15.491Z
Link: CVE-2026-103646
Updated: 2026-10-08T10:57:01.628Z
Status : Deferred
Published: 2026-10-08T06:16:37.957
Modified: 2026-10-08T20:51:18.123
Link: CVE-2026-103646
No data.