Echo Knowledge Base – Documentation, FAQs, AI Chat & AI Search <= 16.011.0 - Missing Authorization

This exploitation research plan focuses on CVE-2026-25402 in the Echo Knowledge Base plugin. Based on the vulnerability description and provided CSS files, the vulnerability likely resides in an AJAX handler related to the "AI Content Analysis" or "AI Chat" features.

1. Vulnerability Summary

The Echo Knowledge Base plugin (up to 16.011.0) contains a Missing Authorization vulnerability. A specific AJAX function registered via wp_ajax_ lacks a current_user_can() check, allowing any authenticated user (Subscriber and above) to execute logic intended only for administrators. Based on the CSS file css/admin-ai-page.css, the vulnerable functionality is likely related to AI Tags, Content Analysis, or AI Search settings.

2. Attack Vector Analysis

• Endpoint: /wp-admin/admin-ajax.php
• Action (Inferred): Likely epkb_save_ai_settings, epkb_ai_reanalyze_content, or epkb_content_analysis_save_tags.
• Authentication: Authenticated (Subscriber level).
• Payload Parameters:
  • action: The vulnerable AJAX action name.
  • _wpnonce or nonce: A security token (likely required but potentially exposed to Subscribers).
  • Feature-specific data (e.g., tag names, setting toggles, or article IDs).

3. Code Flow Analysis (Discovery Steps)

Since the PHP source is not provided, the following discovery steps must be performed by the agent to pinpoint the sink:

1. Identify AJAX Handlers:
   Search for AJAX registrations in the plugin directory:
   grep -r "add_action( 'wp_ajax_" .
2. Filter for Authorization Flaws:
   Check the callback functions for these actions. Specifically, look for those that:
   • Do NOT call current_user_can('manage_options') or a similar capability check.
   • Are related to the "AI" features (matching the CSS file identifiers like epkb-ai-tags-section).
3. Trace AI Tagging Logic:
   The CSS css/admin-ai-page.css mentions .epkb-sidebar-new-tag-input and .epkb-button-delete. Search the PHP code for these strings to find the rendering logic and corresponding AJAX save/delete handlers.

4. Nonce Acquisition Strategy

The plugin likely uses wp_localize_script to pass a nonce to the admin dashboard. Even if a Subscriber cannot access the full AI settings page, the nonce might be localized on a shared admin script or a page the Subscriber can access (like the Knowledge Base frontend or a Subscriber-level dashboard).

1. Identify Nonce Action: Search the PHP for wp_create_nonce. Look for strings like epkb-admin-ajax or epkb_ai_nonce.
2. Find Localization Variable: Look for wp_localize_script. The CSS refers to epkb-content-analysis. The JS variable is likely epkb_admin_vars or epkb_ai_vars.
3. Extraction:
   • Log in as a Subscriber.
   • Navigate to the Knowledge Base home page or the WordPress /wp-admin/ dashboard.
   • Use browser_eval to extract the nonce:
     browser_eval("window.epkb_admin_vars?.ajax_nonce") (Verify variable name in source).

5. Exploitation Strategy

Once the vulnerable action is identified (e.g., epkb_ai_reanalyze_content), follow these steps:

1. Target URL: http://localhost:8080/wp-admin/admin-ajax.php
2. Method: POST
3. Content-Type: application/x-www-form-urlencoded
4. Payload (Example - Re-analysis Trigger):

   action=epkb_ai_reanalyze_content&epkb_kb_id=1&nonce=[EXTRACTED_NONCE]
   

5. Payload (Example - Modifying AI Tags):

   action=epkb_content_analysis_save_tags&tag_name=hacked_tag&article_id=1&nonce=[EXTRACTED_NONCE]
   

6. Test Data Setup

1. Plugin Setup: Install and activate Echo Knowledge Base <= 16.011.0.
2. Content: Create at least one Knowledge Base article (Post Type: echo_knowledge_base).
3. User: Create a user with the Subscriber role.
4. AI Feature: Ensure the AI Content Analysis or Search feature is "enabled" in the plugin settings (as an admin) so the AJAX handlers are active.

7. Expected Results

• Success: The server returns a 200 OK and a JSON success message (e.g., {"status":"success"}).
• Impact: An action usually reserved for admins (like triggering a resource-intensive AI re-scan or modifying metadata/tags) is executed by the Subscriber.

8. Verification Steps

1. Check Database/Options:
   If the exploit modified a setting: wp option get epkb_ai_settings
   If the exploit modified tags: wp post term list [ARTICLE_ID] epkb_post_tag
2. Check Logs:
   If the exploit triggered re-analysis, check for changes in the wp_epkb_ai_log table or relevant metadata updates on articles.

9. Alternative Approaches

• Missing Nonce Check: Check if check_ajax_referer is omitted entirely. If so, no nonce is needed.
• Insecure Nonce Verification: Check if check_ajax_referer is called with die = false and the return value is ignored.
• REST API: Check for endpoints registered via register_rest_route that lack a permission_callback or return true unconditionally. Look for the "AI" namespace in wp-json/.