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.
Weakness
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
Potential Mitigations
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/114.html
- https://cwe.mitre.org/data/definitions/115.html
- https://cwe.mitre.org/data/definitions/151.html
- https://cwe.mitre.org/data/definitions/194.html
- https://cwe.mitre.org/data/definitions/22.html
- https://cwe.mitre.org/data/definitions/57.html
- https://cwe.mitre.org/data/definitions/593.html
- https://cwe.mitre.org/data/definitions/633.html
- https://cwe.mitre.org/data/definitions/650.html
- https://cwe.mitre.org/data/definitions/94.html