CVE-2026-111897: phpMyFAQ Authorization Bypass Vulnerability

CVE-2026-111897 Overview

CVE-2026-111897 is an authorization bypass vulnerability in phpMyFAQ versions 4.2.0-alpha before 4.2.0-beta. The flaw resides in the attachment administration endpoints and allows category-restricted editors to manage attachments belonging to FAQs outside their assigned categories. By supplying arbitrary record_id or attachment ID values, an authenticated user operating in medium permission mode can upload or delete attachments on FAQ entries they are not authorized to modify. The weakness is classified as a missing authorization check [CWE-862].

Critical Impact

Authenticated editors can tamper with or delete attachments across all FAQs, undermining content integrity and enabling unauthorized data manipulation in multi-tenant knowledge bases.

Affected Products

• phpMyFAQ 4.2.0-alpha
• phpMyFAQ releases prior to 4.2.0-beta
• Deployments configured with medium permission mode and category-scoped editors

Discovery Timeline

• 2026-10-17 - CVE-2026-111897 published to NVD
• 2026-10-19 - Last updated in NVD database

Technical Details for CVE-2026-111897

Vulnerability Analysis

phpMyFAQ supports a medium permission model where editors are restricted to specific FAQ categories. Attachment administration endpoints accept a record_id or attachment identifier to determine the target FAQ for upload and delete actions. These endpoints enforce authentication and verify that the caller holds the attachment management permission, but they do not verify that the referenced FAQ belongs to a category the editor is allowed to manage.

As a result, a category-restricted editor can craft requests referencing arbitrary FAQ records. The server executes the requested upload or delete action against the target attachment without validating category scope. This breaks the segmentation model that administrators rely on when delegating knowledge-base content to multiple editor groups.

Root Cause

The root cause is a missing authorization check [CWE-862] on the attachment administration endpoints. The code validates coarse-grained permissions but omits the category ownership check that other FAQ administration flows apply. User-supplied record_id and attachment ID parameters are trusted without cross-referencing the caller's category assignments.

Attack Vector

Exploitation requires an authenticated account with low privileges in medium permission mode. The attacker sends HTTP requests to the attachment upload or delete endpoints with a record_id or attachment ID that points to an FAQ outside their category scope. No user interaction is required. The attacker can replace legitimate attachments with malicious files, delete existing attachments to disrupt the knowledge base, or stage content for further attacks against users who download the modified files.

No verified public exploit code is available at the time of publication. Refer to the GitHub Security Advisory and the VulnCheck Advisory on phpMyFAQ for additional technical context.

Detection Methods for CVE-2026-111897

Indicators of Compromise

• Attachment upload or delete requests from editor accounts targeting record_id values outside their assigned categories.
• Unexpected changes to attachment file hashes on FAQs owned by other category groups.
• Audit log entries showing attachment modifications by users who have never edited the parent FAQ.
• Missing attachments on FAQs that were not modified by the owning editor.

Detection Strategies

• Correlate web server access logs with phpMyFAQ user-to-category mappings to flag attachment endpoint calls that cross category boundaries.
• Enable application-level audit logging for all attachment create and delete operations, including the acting user and target record_id.
• Monitor file integrity on the phpMyFAQ attachment storage directory for unexpected writes or deletions.

Monitoring Recommendations

• Alert on HTTP requests to attachment administration endpoints that return success for users without a documented role on the target FAQ.
• Review phpMyFAQ admin activity reports weekly for cross-category attachment actions.
• Baseline normal editor behavior and alert on volume spikes in attachment upload or delete calls from a single account.

How to Mitigate CVE-2026-111897

Immediate Actions Required

• Upgrade phpMyFAQ to version 4.2.0-beta or later, where the authorization check is enforced on attachment endpoints.
• Audit all editor accounts assigned under medium permission mode and reduce privileges where attachment management is not required.
• Review attachment histories for unauthorized changes since the deployment of 4.2.0-alpha.

Patch Information

The maintainers resolved the vulnerability in phpMyFAQ 4.2.0-beta. Patch details and commit references are published in the GitHub Security Advisory GHSA-hj8v-cg6r-gg6q. Operators running any 4.2.0-alpha build should upgrade immediately.

Workarounds

• Temporarily revoke the attachment management permission from category-restricted editors until the patch is applied.
• Restrict access to the phpMyFAQ /admin interface by source IP or VPN while an upgrade is scheduled.
• Place a web application firewall rule in front of attachment endpoints to validate that the record_id parameter matches the authenticated user's permitted categories.

# Configuration example: restrict admin attachment endpoints at the web server
location ~ ^/admin/api/content/attachments {
    allow 10.0.0.0/8;      # internal admin network only
    deny all;
    auth_basic "phpMyFAQ Admin";
    auth_basic_user_file /etc/nginx/.htpasswd;
}