CVE-2026-86407 Overview
CVE-2026-86407 is an information disclosure vulnerability in the User Registration & Membership WordPress plugin versions prior to 5.2.8. The plugin's membership confirmation page fails to verify that the visitor requesting the page owns the account named in the request. It also does not confirm that any registration or purchase actually occurred. Unauthenticated attackers can retrieve another user's email address, profile fields, role, and membership order details. Exploitation requires the site administrator to have added a user smart tag to that page's configurable message. The plugin's shipped default configuration does not include this smart tag, which limits the practical attack surface.
Critical Impact
Unauthenticated attackers can enumerate registered user data including email addresses, profile fields, roles, and membership order details when the site owner has configured a user smart tag on the confirmation page.
Affected Products
- User Registration & Membership WordPress plugin versions before 5.2.8
- WordPress sites where the plugin's confirmation page has been customized with a user smart tag
- Membership-enabled deployments exposing profile and order metadata
Discovery Timeline
- 2026-09-13 - CVE-2026-86407 published to NVD
- 2026-09-14 - Last updated in NVD database
Technical Details for CVE-2026-86407
Vulnerability Analysis
The vulnerability is classified as Information Exposure [CWE-200]. The membership confirmation page accepts a user identifier from the incoming request and renders account data associated with that identifier. The plugin performs no ownership check tying the requester's session to the referenced account. It also does not validate whether the target account has completed a registration or membership purchase workflow. An unauthenticated visitor can therefore substitute arbitrary user identifiers and read back data belonging to those accounts. Returned fields include the target user's email address, profile fields, assigned role, and membership order details.
Root Cause
The root cause is missing authorization on the confirmation page handler. The plugin trusts the identifier supplied in the request rather than binding data retrieval to the authenticated session. This pattern reflects a broken access control condition where server-side output is generated from client-controlled input without an ownership check.
Attack Vector
An attacker interacts with the public confirmation page over the network. No authentication or user interaction is required. The attack succeeds only when the site owner has customized the confirmation message with a user smart tag that resolves to account data. The default shipped configuration does not include this smart tag, which raises attack complexity and reduces the population of exploitable sites. Refer to the WPScan Vulnerability Report for technical details.
Detection Methods for CVE-2026-86407
Indicators of Compromise
- Repeated requests to the membership confirmation page URL with varying user identifier parameters from a single source address
- Anomalous access patterns to the confirmation endpoint from unauthenticated sessions
- Web server logs showing sequential enumeration of user IDs against the confirmation page
Detection Strategies
- Inventory WordPress installations and identify sites running the User Registration & Membership plugin below version 5.2.8
- Review confirmation page templates for the presence of user smart tags that expose account data
- Correlate access logs against user account identifiers to detect enumeration behavior
Monitoring Recommendations
- Alert on high-volume unauthenticated requests to the plugin's confirmation page
- Monitor egress of email addresses and profile fields from WordPress front-end responses
- Track WordPress plugin inventory and version drift across managed sites
How to Mitigate CVE-2026-86407
Immediate Actions Required
- Upgrade the User Registration & Membership plugin to version 5.2.8 or later
- Audit the confirmation page configuration and remove any user smart tags until the patch is applied
- Review web server logs for prior enumeration attempts against the confirmation endpoint
Patch Information
The vendor has released version 5.2.8 of the User Registration & Membership plugin, which enforces ownership validation on the confirmation page request. Administrators should apply the update through the WordPress plugin management interface. Consult the WPScan Vulnerability Report for release details.
Workarounds
- Remove any user smart tag from the membership confirmation page's configurable message to eliminate the exposed data path
- Restrict access to the confirmation page using a web application firewall rule requiring an authenticated session
- Temporarily disable the plugin on sites where the update cannot be applied immediately
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.