TL;DR

• A contributor‑level IDOR in Accessibility Checker <= 1.30.0 lets an authenticated user (contributor role) access or manipulate objects they should not be allowed to.
• CVE: CVE-2025-57886. Fixed in Accessibility Checker 1.30.1.
• Severity assigned: CVSS 5.4 (Medium / Low patch priority) — impact depends on site setup and how the plugin is used.
• Immediate actions: 1) Update the plugin to 1.30.1+, 2) restrict contributor access to the plugin UI until patched, 3) enable WAF / virtual patching to block unauthorized object access patterns.
• If you run multiple sites, prioritise updating sites where contributor accounts exist for non‑trusted users or where the plugin is mission‑critical.

Background: What is an IDOR and why it matters

Insecure Direct Object References (IDOR) occur when an application exposes an internal object identifier (for example, a database row ID, file path, or token) in a URL or parameter and fails to enforce proper authorization checks server‑side. Attackers who can change that identifier can gain access to data or actions belonging to other users.

Typical consequences of IDOR include:

• Reading or modifying other users’ records (files, reports, settings).
• Performing actions as someone else (posting, deleting, changing configuration) if the endpoint lacks authorization.
• Exfiltrating sensitive data (email addresses, uploaded files).

IDORs often require authentication, but that does not make them harmless. If an attacker can register or obtain a low‑privileged account (contributor/author) they may escalate the impact by accessing resources intended for admins.

The Accessibility Checker issue in plain language

• A security researcher reported an IDOR in the Accessibility Checker plugin that allowed a user with the Contributor role to access objects (reports, scans, or admin resources) tied to other users or global data.
• Plugin versions <= 1.30.0 did not correctly verify that the authenticated user was authorized for the requested object(s).
• The plugin author released 1.30.1 which contains the fix — server‑side authorization checks to ensure requested objects belong to or are permitted for the requester.

Important details:

• The vulnerability requires an authenticated account (Contributor).
• The CVSS is moderate because exploitation requires authentication, but the real impact depends on what the plugin stores and exposes (e.g., attachments, URLs, or scan data).
• The vulnerability is fixed in 1.30.1 — updating removes the risk.

How to quickly check if you’re affected

1. In WordPress admin, go to Plugins → Installed Plugins and find “Accessibility Checker.”
2. If the installed version is <= 1.30.0 you are affected; update to 1.30.1 or later.
3. If you cannot update immediately:
   • Temporarily deactivate the plugin.
   • Or restrict who can access the plugin (see immediate mitigations below).

If you manage many sites, script a version check and prioritise sites where contributor accounts exist for non‑trusted users or where the plugin is mission‑critical.

Exploitation scenarios (what an attacker could do)

• A malicious contributor enumerates object identifiers exposed by the plugin (IDs in URLs, form fields, AJAX parameters) and iterates them to access other users’ scan results or uploaded attachments.
• A contributor could export or view data they should not (private scan data, site diagnostics, URLs containing sensitive tokens).
• If the plugin stores or references uploaded files (attachments for accessibility reports), an attacker may access files uploaded by other users.
• If the plugin exposes configuration or links to external systems, an attacker could gather information useful for follow‑up attacks.

Impact varies — some sites may only expose non‑sensitive accessibility scan metadata, others may expose PII or internal URLs. Inspect how your site uses the plugin.

Detection: How to detect attempted exploitation

Monitor server and application logs for patterns commonly associated with IDOR attempts:

• Repeated requests to the same endpoint with sequential changes to integer identifiers (e.g., id=1, id=2, id=3).
• Contributor‑role accounts issuing requests to admin‑only endpoints or resources they normally cannot view.
• Unusually high rate of access to resource endpoints returning different owner IDs.
• Requests to plugin AJAX endpoints that include object IDs or paths from differing accounts.

Example indicators you can search for in access logs (replace plugin endpoints with the actual endpoint path on your site):

• Query string patterns: /wp-admin/admin-ajax.php?action=ac_get_report&report_id=123
• Sequential numeric requests from one IP or user account
• 200 responses to resource accesses by contributor accounts which normally should be forbidden

If you find suspicious activity, consider rotating credentials for affected users and follow the incident response steps below.

Immediate mitigations (what to do right now)

1. Update the plugin to 1.30.1 or later (preferred, fast, and complete fix).
2. If you cannot update immediately:
   • Remove or deactivate the plugin on high‑risk sites.
   • Limit Contributor role capabilities temporarily (see capability hardening below).
   • Disable plugin endpoints by blocking access with your WAF until you can update (pattern‑based rule for AJAX endpoints).
3. Audit user accounts:
   • Remove or convert unneeded Contributor accounts.
   • Check for suspicious accounts created recently.
4. Harden uploads and file access:
   • Ensure uploaded files are stored in locations that enforce permission checks.
   • Prevent direct listing or public access to internal upload paths where possible (use signed URLs or rewrite rules).
5. Monitor logs and set alerts for enumeration patterns described in the Detection section.
6. Rotate sensitive secrets if you suspect exposure (API tokens, keys, or integration credentials).

Capability hardening: practical WordPress steps

If you need a quick server‑side stopgap while applying the plugin update, you can modify contributor capabilities to temporarily narrow their allowed actions. The safest approach is time‑limited and reversible. Test changes on a staging site first.

<?php
/*
Plugin Name: Temp Contributor Capability Hardening
Description: Temporarily remove risky capabilities from contributor role.
Version: 0.1
*/

// RUN ONLY TEMPORARILY: remove sensitive capabilities from contributors.
add_action('init', function () {
    $role = get_role('contributor');
    if ( ! $role ) {
        return;
    }
    // Example: remove edit_published_posts if you want to prevent some actions
    // $role->remove_cap('edit_published_posts');

    // A conservative approach is to prevent access to the plugin admin page,
    // using a capability that only editors/admins have:
    add_filter('map_meta_cap', function($caps, $cap, $user_id, $args) {
        if ( in_array($cap, ['access_ac_plugin_admin']) ) {
            $caps = ['manage_options']; // require admin
        }
        return $caps;
    }, 10, 4);
});
?>

Notes:

• Do not rely on this as a long‑term fix. Update the plugin as soon as possible.
• Test changes on a staging site first. Capability adjustments can affect editorial workflows.

WAF and Virtual Patching: how they help, and what to configure

A WAF can protect you while you apply the official fix by blocking the exploitation patterns that the IDOR relies on. Virtual patching (vPatching) means deploying a protective rule that intercepts malicious requests and prevents them from reaching the vulnerable code.

Key WAF rules to deploy for IDOR protection:

• Parameter tampering detection: block requests where object identifiers are changed in ways uncommon to legitimate usage (rapid enumeration of sequential IDs).
• Role‑based endpoint protection: block requests to plugin admin or AJAX endpoints made by Contributor role sessions or by requests missing valid admin cookies/nonces.
• Request rate‑limiting: throttle an authenticated account that is making many sequential object access requests.
• Block common attack vectors: deny access to suspicious referers, known bad IPs, or requests with known automation fingerprints.

Recommended temporary rule: inspect requests to the plugin’s endpoints and return a 403 when the request is made by a non‑owner contributor for object identifiers that belong to another user. Virtual patches are temporary protective measures until you install the official update and should not replace the upstream fix.

Incident response: If you suspect you were exploited

If you find signs of abuse related to this vulnerability, follow a standard incident response workflow:

1. Contain:
   • Immediately update the plugin (1.30.1+) on affected sites or disable the plugin temporarily.
   • If update is not possible, enforce WAF rules to block access to the vulnerable endpoints and suspend suspicious contributor accounts.
2. Preserve evidence:
   • Save relevant logs (webserver, PHP, plugin logs) and copies of affected files for forensics.
   • Note timestamps, IP addresses, and user account identifiers.
3. Investigate:
   • Look for unexpected file uploads, new admin users, or malicious scheduled jobs.
   • Check database tables for unauthorized changes associated with plugin object IDs.
4. Eradicate:
   • Remove any webshells, backdoors, or malicious cron jobs.
   • Rotate API keys and credentials that may have been exposed.
5. Recover:
   • Restore cleaned backups if necessary and update all plugins and WP core.
   • Reapply stricter user controls and credentials.
6. Review and Learn:
   • Conduct a root‑cause analysis to understand how access occurred and what controls failed.
   • Update incident playbooks and apply lessons learnt across all your sites.

If you are uncertain about the scope of compromise, engage a professional incident responder.

Longer‑term hardening and best practices

• Principle of least privilege: limit contributor permissions only to what’s needed. Remove the ability to upload files unless strictly required.
• Plugin governance: only install plugins from trusted sources and keep an inventory of plugins and versions across sites.
• Regular scanning and SCA: use software composition analysis or plugin monitoring tools to detect vulnerable versions proactively.
• Staging and testing: deploy plugin updates first in a staging environment; test quickly and then roll out.
• Two‑factor authentication: require 2FA for all accounts with contributor and above roles where possible.
• Audit trails & alerting: centralise logs and set alerts for unusual user behavior (high request rates, sequential ID access).
• Backup and restore plan: ensure backups are up‑to‑date and regularly tested.

Example developer fix pattern

At a conceptual level, the fix for an IDOR is always to verify ownership or permissions server‑side before returning an object. A typical check in WordPress plugin code:

$report_id = intval( $_GET['report_id'] ?? 0 );
$report = get_report_by_id( $report_id );

if ( ! $report ) {
    wp_send_json_error( 'Report not found', 404 );
}

// Ensure current user is authorized to access this report
$current_user_id = get_current_user_id();
if ( $report->owner_id !== $current_user_id && ! current_user_can('manage_options') ) {
    wp_send_json_error( 'Forbidden', 403 );
}

// Continue returning the requested data
wp_send_json_success( $report->to_array() );

Key points:

• Never rely on client‑side controls (JS checks, hidden fields) for authorization.
• Always validate and sanitize incoming IDs.
• Use capability checks appropriate to the object sensitivity; owner checks are common.

Detection rules and WAF signatures (high level)

If you manage a WAF, consider rules that detect and intercept the following behaviours:

• Authenticated requests to plugin endpoints where a parameter like report_id, scan_id, file_id appears, and the requesting user is not the owner.
• Requests with sequential integer IDs from the same IP or account within a short window (enumeration).
• AJAX calls to admin-ajax.php carrying plugin-specific action names with mismatched cookie/capability flows.
• Requests where Contributor role cookies are used to fetch admin-only resources.

Implementations vary by WAF technology. If your WAF supports user role detection (via session cookies + server validation), you can create role‑based allow/deny rules. Otherwise use behavioural and parameter rules.

Risk assessment for different site types

• Small brochure sites with only editors and admins: Low risk unless contributors are used.
• Multi‑author blogs and membership sites: Higher risk because contributor or member roles may exist and be usable to exploit IDOR.
• Sites with plugin integrations storing sensitive data: Elevated risk if plugin objects include PII or private URLs.
• Agency or client sites with many contributors: Prioritise patching across the fleet.

Always evaluate your site’s specific exposure and available contributor accounts.

Frequently asked questions

Q: I don’t use the Accessibility Checker plugin — am I affected?

A: No. Only sites running Accessibility Checker versions <= 1.30.0 are impacted.

Q: I updated to 1.30.1 but still see suspicious accesses in logs — what now?

A: Update is essential. After updating, continue monitoring logs and scan for indicators of compromise. If you suspect a successful exploit prior to patching, follow the incident response steps above.

Q: Is virtual patching safe to rely on?

A: Virtual patching is an excellent interim protective measure but not a replacement for the upstream fix. Apply virtual patching to buy time and reduce exposure while you update.

Q: Should I disable contributor accounts instead?

A: For critical short‑term risk reduction you can downgrade or suspend untrusted contributor accounts. This may disrupt editorial workflows, so balance risk and operations.

Checklist: What to do now (step‑by‑step)

1. Confirm plugin version. If <= 1.30.0, update to 1.30.1+ immediately.
2. If you cannot update right away:
   • Deactivate the plugin OR
   • Deploy WAF rules / virtual patch to block targeted endpoints OR
   • Restrict contributor accounts temporarily.
3. Audit contributor roles and remove unneeded accounts.
4. Monitor logs for enumeration patterns and unusual file downloads.
5. Run a malware and file integrity scan after patching to check for signs of compromise.
6. Ensure backups are verified and stored offsite.
7. Schedule plugin updates and keep an inventory of all installed plugins.