CVE-2026-89406: Modula Gallery Information Disclosure Flaw

CVE-2026-89406 Overview

CVE-2026-89406 affects the Modula Image Gallery – Photo Grid & Video Gallery plugin for WordPress through version 3.0.1. The vulnerability allows unauthenticated attackers to enumerate private modula-gallery posts and retrieve their member attachments. The flaw stems from missing authorization checks [CWE-862] in the Modula_Meta::add_metas() function, which is hooked to wp_head on every frontend request. Attackers can recover an image's title, description, dimensions, and original upload URL through Open Graph and Twitter meta tags, enabling direct download of private image bytes without authentication.

Critical Impact
Unauthenticated attackers can enumerate private gallery contents and download original private image files directly from the WordPress media library.

Affected Products

Modula Image Gallery – Photo Grid & Video Gallery plugin for WordPress
All versions up to and including 3.0.1
WordPress sites exposing the Modula plugin on frontend requests

Discovery Timeline

2026-09-25 - CVE-2026-89406 published to the National Vulnerability Database (NVD)
2026-09-25 - Last updated in NVD database

Technical Details for CVE-2026-89406

Vulnerability Analysis

The vulnerability resides in the Modula_Meta::add_metas() function within includes/public/meta/class-modula-meta.php. The function hooks into wp_head on every frontend request and invokes get_post( $_GET['modula_gallery_id'] ) without validating the gallery's post_status or verifying whether the requester has capability to read it.

The plugin's intended input guard contains a logic bug. The check empty('modula_gallery_id') tests a nonempty string literal rather than the actual GET parameter, so the condition always evaluates to false and the guard never triggers. The only object validation performed is a post_type === 'modula-gallery' check, which does not consider publication status or user permissions.

Because no is_user_logged_in() or current_user_can('read_post', $gallery_id) check runs, private gallery posts are treated identically to published ones. The response then emits Open Graph and Twitter Card meta tags containing the full attachment URL, title, description, and dimensions.

Root Cause

The root cause is Missing Authorization [CWE-862]. The plugin fails to enforce access control on an input-driven data lookup. The intended empty-string guard was coded against a literal rather than the request parameter, defeating the only pre-check.

Attack Vector

An unauthenticated remote attacker sends an HTTP GET request to any frontend page with a modula_gallery_id query parameter containing an enumerated post ID. The server renders Open Graph meta tags into the response HTML that reveal the private attachment's original upload URL. The attacker then issues a direct GET against the WordPress uploads path to retrieve the private image bytes.

See the WordPress Modula Meta Class source and Wordfence Vulnerability Report for technical details on the affected code path.

Detection Methods for CVE-2026-89406

Indicators of Compromise

Unauthenticated HTTP GET requests containing the modula_gallery_id query parameter in access logs
Sequential or enumerated numeric values for modula_gallery_id indicating ID brute-forcing
Repeated requests from a single source IP against varied frontend URLs with the parameter appended
Direct downloads of /wp-content/uploads/ files immediately following requests containing modula_gallery_id

Detection Strategies

Parse web server logs for query strings containing modula_gallery_id= originating from unauthenticated sessions
Correlate meta-tag-exposing frontend requests with subsequent direct attachment downloads from the same client IP
Alert on HTTP response bodies containing og:image or twitter:image tags that reference attachment URLs attached to non-published posts

Monitoring Recommendations

Enable verbose access logging on WordPress frontends running Modula and forward logs to a centralized SIEM
Monitor for anomalous volumes of requests targeting a single plugin query parameter
Baseline normal gallery traffic and alert on deviations consistent with ID enumeration

How to Mitigate CVE-2026-89406

Immediate Actions Required

Update the Modula Image Gallery plugin to a version newer than 3.0.1 as soon as the patched release is available from the vendor
Audit WordPress access logs for prior requests containing modula_gallery_id to assess whether private galleries were enumerated
Rotate or re-upload any sensitive images that may have been exposed through the private gallery disclosure

Patch Information

The vendor committed a fix tracked in the WordPress Modula Changeset Overview. Site administrators should apply the plugin update through the WordPress admin dashboard or via WP-CLI once the fixed version propagates to the WordPress.org plugin repository.

Workarounds

Temporarily deactivate the Modula Image Gallery plugin until a patched version is installed
Deploy a web application firewall (WAF) rule to block unauthenticated requests containing the modula_gallery_id query parameter
Restrict access to /wp-content/uploads/ paths containing sensitive imagery using server-level authentication or signed URLs

bash

# Example WAF/Nginx rule to block unauthenticated use of the vulnerable parameter
if ($arg_modula_gallery_id) {
    return 403;
}