CVE-2026-103646
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. 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.
INFO
Published Date :
Oct. 8, 2026, 6:16 a.m.
Last Modified :
Oct. 8, 2026, 6:16 a.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-103646
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Update The Ultimate Multisite WordPress plugin to version 2.17.0.
- Verify that the checkout form does not have a password field.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-103646.
| URL | Resource |
|---|---|
| https://wpscan.com/vulnerability/a05da0ad-5d92-406f-b182-b3ed1f8389f3/ |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-103646 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-103646
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-103646 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-103646 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Oct. 08, 2026
Action Type Old Value New Value Added 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. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/103xxx/CVE-2026-103646.json">CVE-2026-103646</a> Added Reference https://wpscan.com/vulnerability/a05da0ad-5d92-406f-b182-b3ed1f8389f3/