Reported vulnerability
Ultimate Multisite <= 2.16.0 - Unauthenticated Arbitrary Account Takeover
Published 6 Oct 2026
Updated 13 Oct 2026
CVE-2026-103646
Compare your installed software with the affected versions below. Follow the source’s remediation guidance and test an available update after taking a backup. A database entry describes a reported issue; it does not establish whether a particular website has been compromised.
Does this affect my version?
Check your installed version against this advisory. This compares the report’s version ranges and does not scan your website.
Wordfence advisory
high · CVSS 7.3The Ultimate Multisite plugin for WordPress is vulnerable to Account Takeover in all versions up to, and including, 2.16.0. This is due to missing email normalization before the duplicate-account lookup combined with the absence of a require_new_user guard, allowing a submitted email to be matched to and linked with an existing WordPress user account without authentication. This makes it possible for unauthenticated attackers to log in as any existing WordPress user, including a Network Super Admin, by submitting their known email address through a passwordless checkout form and having the plugin link the unauthenticated checkout session to that existing account. A checkout form must be configured without a password field (auto-generated password mode), and the targeted WordPress account must have no existing customer record in the plugin.
Severity vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Ultimate Multisite – WordPress Multisite SaaS & WaaS Platform
- Software
- plugin · ultimate-multisite
- Affected versions
- Start version unspecified, through 2.16.0
- Fix availability
- Fix available
- Fixed versions
- 2.17.0
Recommended action
Update to version 2.17.0, or a newer patched version
Further references (1)
Data sources and licences
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Read licence termsSource: Wordfence
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Get help with this issueQuestions about this vulnerability
Which versions of Ultimate Multisite – WordPress Multisite SaaS & WaaS Platform are affected?
Wordfence lists these affected versions: Start version unspecified, through 2.16.0. Use the version checker above to compare your installed release with this report.
Is a fix available for Ultimate Multisite – WordPress Multisite SaaS & WaaS Platform?
Wordfence reports a fix for this issue in Ultimate Multisite – WordPress Multisite SaaS & WaaS Platform. It lists these fixed versions: 2.17.0. Back up your website and test the recommended update before applying it to your live site.
Where can I find my installed plugin version?
In WordPress, open Plugins > Installed Plugins and find the version shown beneath the plugin name.
Does an affected version mean my website has been hacked?
An affected version means the installed release matches a vulnerability described in this report. It does not show whether anyone has exploited it on your website. The checker compares version numbers with stored reports; it does not inspect your website.
Other reports for the same product
These reports cover at least one of the same plugins, themes or WordPress core. Check each report’s affected versions separately.