CVE-2026-39690: Author Avatars Auth Bypass Vulnerability

CVE-2026-39690 Overview

CVE-2026-39690 is a Missing Authorization vulnerability affecting the Author Avatars List/Block WordPress plugin developed by Paul Bearne. This security flaw allows attackers to exploit incorrectly configured access control security levels, potentially enabling unauthorized access to sensitive information or functionality within WordPress installations using the vulnerable plugin.

The vulnerability stems from broken access control mechanisms within the plugin, which fails to properly verify user authorization before performing certain actions. This allows unauthenticated remote attackers to bypass security restrictions and access resources that should be protected.

Critical Impact

Unauthorized users can exploit misconfigured access controls to gain access to protected resources, potentially exposing sensitive author information or bypassing intended security restrictions in WordPress sites.

Affected Products

• Author Avatars List/Block plugin version 2.1.25 and earlier
• WordPress installations using the affected plugin versions

Discovery Timeline

• 2026-04-08 - CVE CVE-2026-39690 published to NVD
• 2026-04-08 - Last updated in NVD database

Technical Details for CVE-2026-39690

Vulnerability Analysis

This vulnerability is classified under CWE-862 (Missing Authorization), indicating that the plugin fails to perform proper authorization checks before granting access to protected functionality or resources.

The flaw allows remote attackers without any prior authentication to exploit the misconfigured access control mechanisms. The attack can be executed over the network with low complexity, requiring no user interaction. While the vulnerability does not allow attackers to modify data or cause service disruption, it can lead to unauthorized disclosure of information that should be protected.

WordPress plugins that handle user information, such as author avatars and profiles, must implement robust authorization checks to ensure that only authenticated and authorized users can access sensitive data or administrative functions.

Root Cause

The root cause of CVE-2026-39690 is the absence of proper authorization checks within the Author Avatars List/Block plugin. The plugin fails to verify whether a user has the necessary permissions before allowing access to certain endpoints or functionality. This missing authorization check creates a broken access control condition that can be exploited by malicious actors.

The vulnerability exists in versions up to and including 2.1.25 of the plugin, affecting WordPress sites that have installed this component for displaying author avatars and lists.

Attack Vector

The attack vector for this vulnerability is network-based, meaning an attacker can exploit it remotely without requiring local access to the target system. The exploitation characteristics include:

• Network-accessible: Attackers can target vulnerable WordPress installations over the internet
• No authentication required: The vulnerability can be exploited without valid credentials
• No user interaction needed: Exploitation does not require a legitimate user to perform any action
• Information disclosure risk: Successful exploitation may reveal protected information

Attackers could craft specific requests to the vulnerable plugin endpoints to bypass access controls and retrieve information that should require authentication or elevated privileges to access.

Detection Methods for CVE-2026-39690

Indicators of Compromise

• Unusual requests to Author Avatars plugin endpoints from unauthenticated sources
• Unexpected access patterns to author profile or avatar-related functionality
• Log entries showing unauthorized access attempts to protected plugin resources
• Anomalous HTTP requests targeting WordPress plugin directories

Detection Strategies

• Monitor WordPress access logs for suspicious requests to the author-avatars plugin paths
• Implement web application firewall (WAF) rules to detect and block unauthorized access attempts
• Review WordPress audit logs for unexpected access to author-related data
• Deploy file integrity monitoring to detect unauthorized plugin modifications

Monitoring Recommendations

• Enable detailed logging for WordPress and the Author Avatars plugin
• Configure alerts for failed authorization attempts or unusual access patterns
• Regularly audit user access logs for signs of exploitation attempts
• Monitor network traffic for unusual patterns targeting WordPress installations

How to Mitigate CVE-2026-39690

Immediate Actions Required

• Update the Author Avatars List/Block plugin to the latest patched version immediately
• Review WordPress access logs for signs of potential exploitation
• Consider temporarily disabling the plugin if a patch is not yet available
• Implement additional access controls at the web server or WAF level

Patch Information

The vulnerability affects Author Avatars List/Block plugin versions through 2.1.25. Site administrators should update to a patched version as soon as one becomes available. For detailed vulnerability information and patch status, refer to the Patchstack Vulnerability Report.

Workarounds

• Restrict access to plugin endpoints using web server configuration or firewall rules
• Implement additional authentication requirements at the server level for sensitive plugin functionality
• Use a WordPress security plugin to add extra access control layers
• Consider removing the plugin entirely if it is not essential to site functionality

# Example: Restrict access to plugin directory via .htaccess
<Directory "/var/www/html/wp-content/plugins/author-avatars">
    Require all denied
    # Allow only authenticated WordPress admin users
    Require valid-user
</Directory>