CVE-2026-24633: Add Expires Headers Auth Bypass Flaw

CVE-2026-24633 Overview

CVE-2026-24633 is a Missing Authorization vulnerability in the WordPress plugin "Add Expires Headers & Optimized Minify" developed by Passionate Brains. This vulnerability allows attackers to exploit incorrectly configured access control security levels, potentially leading to unauthorized access to plugin functionality. The flaw stems from broken access control mechanisms that fail to properly verify user permissions before executing sensitive operations.

Critical Impact

Unauthenticated attackers can bypass access controls and interact with plugin functionality that should require proper authorization, potentially exposing sensitive configuration data.

Affected Products

• Add Expires Headers & Optimized Minify plugin versions from n/a through 3.1.0
• WordPress installations using the affected plugin versions

Discovery Timeline

• 2026-01-23 - CVE CVE-2026-24633 published to NVD
• 2026-01-26 - Last updated in NVD database

Technical Details for CVE-2026-24633

Vulnerability Analysis

This vulnerability represents a broken access control flaw classified under CWE-862 (Missing Authorization). The Add Expires Headers & Optimized Minify plugin fails to implement proper authorization checks before allowing access to certain plugin functionality. Without adequate permission validation, unauthenticated users or users with insufficient privileges can access features or data that should be restricted.

The vulnerability is network-exploitable without requiring any user interaction or authentication, though the scope is limited to read access of potentially low-sensitivity information. This type of access control misconfiguration is common in WordPress plugins where developers may implement nonce verification for CSRF protection but neglect to add capability checks to verify the user has appropriate permissions.

Root Cause

The root cause of this vulnerability is the absence of proper authorization checks (capability checks in WordPress terminology) within the plugin's codebase. WordPress plugins should use functions like current_user_can() to verify that the requesting user has the appropriate permissions before processing requests that modify settings or expose sensitive functionality.

In this case, the plugin appears to expose functionality without validating whether the requesting user has the necessary administrative capabilities, allowing any user—including unauthenticated visitors—to interact with endpoints that should be restricted.

Attack Vector

The attack can be conducted remotely over the network by any unauthenticated user. An attacker can send crafted requests directly to vulnerable plugin endpoints without needing valid credentials or any form of user interaction. The vulnerability allows read access to information that should be protected, though it does not appear to allow data modification or system compromise.

Exploitation typically involves identifying the vulnerable AJAX actions or REST API endpoints exposed by the plugin and sending direct requests to these endpoints without the required authorization headers or session tokens that would normally indicate a privileged user.

Detection Methods for CVE-2026-24633

Indicators of Compromise

• Unusual HTTP requests to WordPress AJAX endpoints (/wp-admin/admin-ajax.php) with plugin-specific action parameters from unauthenticated sources
• Increased access attempts to plugin configuration endpoints from external IP addresses
• Log entries showing successful responses to plugin endpoints that should require authentication

Detection Strategies

• Monitor WordPress access logs for requests to admin-ajax.php with action parameters related to the Add Expires Headers plugin
• Implement Web Application Firewall (WAF) rules to detect and block unauthorized access attempts to plugin endpoints
• Review server logs for patterns of reconnaissance activity targeting WordPress plugin endpoints

Monitoring Recommendations

• Enable detailed logging for WordPress AJAX requests and review regularly for suspicious activity
• Deploy endpoint monitoring solutions to track unusual access patterns to administrative functionality
• Configure alerts for any successful requests to plugin endpoints from non-authenticated sessions

How to Mitigate CVE-2026-24633

Immediate Actions Required

• Update the Add Expires Headers & Optimized Minify plugin to the latest patched version when available
• Review WordPress user permissions and ensure principle of least privilege is applied
• Consider temporarily disabling the plugin if no patch is available and the functionality is not critical
• Implement WAF rules to restrict access to vulnerable endpoints

Patch Information

Review the Patchstack Vulnerability Report for the latest patch status and remediation guidance. Update the plugin through the WordPress admin dashboard once a patched version becomes available from the vendor.

Workarounds

• Restrict access to WordPress admin-ajax.php endpoints using server-level access controls (.htaccess for Apache or nginx configuration)
• Implement IP-based restrictions to limit access to administrative endpoints from trusted networks only
• Use a security plugin that provides capability to block unauthorized AJAX requests
• Consider using a Web Application Firewall to filter malicious requests targeting the vulnerable plugin

# Apache .htaccess example to restrict admin-ajax.php access
# Add to WordPress root .htaccess file

<Files admin-ajax.php>
    Order Deny,Allow
    Deny from all
    # Allow from specific trusted IPs
    Allow from 192.168.1.0/24
    Allow from 10.0.0.0/8
</Files>