CVE-2026-39476: User Feedback Auth Bypass Vulnerability

CVE-2026-39476 Overview

CVE-2026-39476 is a Missing Authorization vulnerability affecting the User Feedback plugin (userfeedback-lite) for WordPress, developed by Syed Balkhi. This broken access control vulnerability allows attackers to exploit incorrectly configured access control security levels, potentially enabling unauthorized actions within WordPress installations using the vulnerable plugin.

Critical Impact

Unauthorized users may bypass access controls to perform privileged operations within the User Feedback plugin, potentially compromising site integrity and user data.

Affected Products

• User Feedback (userfeedback-lite) WordPress Plugin versions through 1.10.1
• WordPress installations with the User Feedback plugin enabled

Discovery Timeline

• 2026-04-08 - CVE-2026-39476 published to NVD
• 2026-04-08 - Last updated in NVD database

Technical Details for CVE-2026-39476

Vulnerability Analysis

This vulnerability is classified as CWE-862 (Missing Authorization), a common weakness where the application fails to perform authorization checks before allowing access to protected functionality. In the context of the User Feedback WordPress plugin, this manifests as broken access control that can be exploited by attackers to bypass intended security restrictions.

The vulnerability affects all versions of the User Feedback plugin up to and including version 1.10.1. WordPress plugins that fail to implement proper capability checks on administrative functions create opportunities for both authenticated and potentially unauthenticated users to access restricted functionality.

Root Cause

The root cause of this vulnerability is improper implementation of authorization controls within the User Feedback plugin. WordPress provides a robust capabilities and roles system that plugins must properly leverage to restrict access to sensitive functionality. When these authorization checks are missing or incorrectly configured, security boundaries can be bypassed.

Missing authorization vulnerabilities typically occur when:

• Plugin endpoints lack proper current_user_can() checks
• AJAX handlers fail to verify user permissions before processing requests
• Administrative functions are exposed without capability verification

Attack Vector

An attacker can exploit this vulnerability by sending crafted requests to plugin endpoints that lack proper authorization checks. Because the access control security levels are incorrectly configured, these requests may be processed without validating whether the user has appropriate permissions.

The attack does not require advanced technical skills once the vulnerable endpoints are identified. Exploitation could allow attackers to access or modify feedback data, change plugin settings, or perform other actions that should be restricted to administrators.

For detailed technical information about this vulnerability, refer to the Patchstack WordPress Vulnerability Report.

Detection Methods for CVE-2026-39476

Indicators of Compromise

• Unexpected modifications to User Feedback plugin settings or configurations
• Unusual API calls or requests to User Feedback plugin endpoints from unauthorized users
• Anomalous activity in WordPress logs showing access to plugin functions by low-privilege or unauthenticated users
• Unauthorized export or access to feedback data collected by the plugin

Detection Strategies

• Monitor WordPress access logs for requests to userfeedback-lite plugin endpoints from unexpected sources or user roles
• Implement Web Application Firewall (WAF) rules to detect and block suspicious requests targeting the plugin
• Review WordPress audit logs for configuration changes to the User Feedback plugin made by non-administrator users
• Deploy endpoint detection solutions to identify exploitation attempts against WordPress installations

Monitoring Recommendations

• Enable comprehensive WordPress activity logging to capture all plugin-related events
• Configure alerts for any changes to User Feedback plugin settings outside of normal administrative activity
• Monitor for bulk access or export of feedback data that may indicate data exfiltration
• Regularly audit user roles and capabilities to ensure principle of least privilege is maintained

How to Mitigate CVE-2026-39476

Immediate Actions Required

• Update the User Feedback plugin to a patched version as soon as one becomes available
• Temporarily disable the User Feedback plugin if it is not critical to site operations until a patch is released
• Implement additional access controls at the web server or WAF level to restrict access to plugin endpoints
• Review WordPress user accounts and remove any unnecessary administrative privileges

Patch Information

Consult the Patchstack WordPress Vulnerability Report for the latest patch information and updates from the plugin maintainers. Ensure that automatic updates are enabled for WordPress plugins or establish a regular update schedule.

Workarounds

• Restrict access to the WordPress admin area by IP address if feasible for your environment
• Use a WordPress security plugin to add additional authorization layers and logging
• Implement .htaccess rules to restrict direct access to plugin files and directories
• Consider using a maintenance mode or temporarily deactivating the plugin until patched

# Example: Restrict access to plugin directory via .htaccess
# Add to wp-content/plugins/userfeedback-lite/.htaccess
<Files "*.php">
    Order Deny,Allow
    Deny from all
    Allow from 127.0.0.1
</Files>