CVE-2026-77194: Simple Membership <= 4.8.1 - Unauthenticated Authentication Bypass to Administrator Account Takeover via Multisite Identity Binding
The Simple Membership plugin for WordPress is vulnerable to Authentication Bypass leading to Administrator Account Takeover in versions up to, and including, 4.8.0. This is due to improper identity verification during the public registration flow in WordPress Multisite environments, where the plugin binds new Simple Membership records to existing global WordPress users based solely on matching username and email, without requiring password verification or ownership proof, and fails to properly detect Administrator roles on child sites. This makes it possible for unauthenticated attackers to take over Administrator accounts on child sites in a Multisite network by registering a Simple Membership account with a victim's credentials on a site where public registration is enabled, then updating the victim's global WordPress password through the profile edit functionality. The vulnerability was partially patched in version 4.8.1.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
WordPress plugin: Simple Membershipto a version that resolves this vulnerability.Fixed in 4.8.1 - Configuration
Disable public registration in the WordPress Multisite so unauthenticated attackers cannot create Simple Membership records via the public registration flow used for the authentication bypass and Administrator account takeover.
WordPress Multisite public registration = disabled
Event History
Frequently Asked Questions
Which environments are exposed to this issue?
The issue affects WordPress Multisite environments using the Simple Membership plugin, where public registration is enabled on a child site. The described impact is takeover of Administrator accounts on child sites.
What does an attacker need to exploit it?
An attacker does not need to authenticate or interact with a victim. They need a target site with public registration enabled and must register a Simple Membership account using the victim's matching WordPress username and email address.
How does the account takeover occur?
The registration flow can bind the attacker's new Simple Membership record to an existing global WordPress user without password verification or proof of account ownership. The attacker can then use profile editing functionality to change that global WordPress user's password.
Are systems running version 4.8.1 fully remediated?
No full remediation status is established by the available information. Version 4.8.1 is described as only partially patching the vulnerability; versions through 4.8.0 are identified as vulnerable.