Tên plugin	The Events Calendar
Type of Vulnerability	Information Disclosure
CVE Number	CVE-2025-9808
Tính cấp bách	Thấp
CVE Publish Date	2025-09-15
Source URL	CVE-2025-9808

Urgent: The Events Calendar (<= 6.15.2) — Missing Authorization Leads to Password‑Protected Information Disclosure (CVE-2025-9808)

On 15 September 2025 a security advisory was published for The Events Calendar plugin (a widely used WordPress events plugin). The issue (recorded as CVE‑2025‑9808) affects versions up to and including 6.15.2 and is classified as Broken Access Control — specifically, a missing authorization check that can allow unauthenticated users to retrieve information that should have been protected by WordPress post passwords.

As a WordPress security team and the maintainers of WP‑Firewall, we want to explain what this means for your site, how to quickly determine whether you’re affected, practical and safe mitigations you can apply immediately, and long‑term recommendations to reduce risk from similar issues going forward.

Note: an official fix was released in The Events Calendar 6.15.3. Updating is the recommended resolution. If you cannot update immediately, this article explains responsible mitigations you can apply today.

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Executive summary (TL;DR)

• Vulnerability: Broken Access Control / Missing authorization for access to password‑protected event content.
• Impact: Unauthenticated attackers may be able to read content that site owners intended to protect with WordPress post passwords (events or event metadata).
• Affected versions: The Events Calendar <= 6.15.2.
• Fixed in: The Events Calendar 6.15.3 — update as soon as possible.
• CVSS score published: 5.3 (medium / low depending on context); required privilege: unauthenticated.
• Immediate actions: update the plugin; if you cannot, apply temporary virtual patches via your WAF or block specific endpoints; audit logs for suspicious access to event API endpoints; rotate any exposed secrets if applicable.

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Why this is serious — but not catastrophic

Password‑protected posts are a core WordPress feature to quickly restrict public access to specific posts or pages using a simple post password. Many site owners rely on that pattern to share events with a limited audience, or to hide draft/preview content.

A missing authorization check in a plugin that exposes event data — for example, via REST or AJAX endpoints — means a GET or POST request to an API endpoint could return content that should have required the post password. The attacker does not need to be logged in, and there is no required privilege. The property that makes this particularly bad is that disclosure can be silent (the owner may not notice) and automated scanners can enumerate vulnerable sites at scale.

However, the measured CVSS and classification indicate the issue is not a remote code execution or immediate site takeover vector by itself. The main risk is exposure of content (sensitive event details, attendee info if stored, notes, or internal links). In the presence of other insecure elements (weak credentials, vulnerable plugins allowing file upload, etc.), information disclosure can be a foothold or stepping stone.

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How the vulnerability works (high level — no exploit details)

• The plugin exposes resources through public endpoints (for example, REST API routes or admin‑ajax actions) that accept parameters identifying an event (post ID, slug, etc.).
• When a post is password‑protected, WordPress normally requires that the visitor submit the post password before the protected content is returned. That check is enforced by core template functions and by the post protection mechanisms.
• In this case, certain plugin endpoints returned protected fields (title, content, metadata) without verifying whether the caller had the correct post password or was otherwise authorized. In other words, an authorization guard was missing or bypassable on server side logic.
• The result: unauthenticated requests to specific endpoint(s) could receive data that should have been blocked by the post password protection.

We will not publish step‑by‑step exploit instructions — responsible disclosure practices prohibit providing actionable exploit techniques. Instead the rest of this post focuses on detection, mitigation, and response.

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Am I affected? How to check quickly

1. Check your plugin version:
   • Login to WP Admin → Plugins, or check the filesystem plugin header in /wp-content/plugins/the-events-calendar/.
   • If The Events Calendar plugin version is 6.15.2 or lower, you are in the vulnerable set. 6.15.3 contains the fix.
2. Look for evidence in access logs:
   • Search your webserver or WAF logs for requests to event-related endpoints. Common indicators include patterns like:
     • Requests to REST routes beginning with /wp-json/tribe/ hoặc /wp-json/tribe/events/
     • Requests to admin-ajax with hoạt động parameters referencing tribe or events (e.g., action=tribe_*)
   • Search for suspicious, repeated requests that include post IDs or slugs for password‑protected events.
3. Check whether you use password‑protected events:
   • If you use WordPress post passwords for events (visible in the editor under “Visibility” → “Password Protected”), those entries are the ones at risk of disclosure.
4. Run a controlled test in a staging environment:
   • Do not test exploitation against production directly. Set up a staging copy (same plugin version) and use controlled requests to see whether a REST endpoint returns protected content without authentication. If you see sensitive content returned without supplying the expected password, the staging site reproduces the vulnerability and your production site likely is vulnerable too.

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Immediate, responsible mitigation steps

If you host a site running The Events Calendar <= 6.15.2, prioritize the following in order:

1. Update the plugin to 6.15.3 (recommended)
   • The vendor issued a fix in 6.15.3. Updating removes the vulnerability entirely from your site.
   • Always test the update on staging first if you have complex customizations.
2. If you cannot update immediately, apply one or more temporary mitigations:
   • Disable public API endpoints used by the plugin that might expose event content.
     • For example, deregister or remove REST endpoints you do not need.
     • Sample safe approach (add to a simple mu-plugin or theme functions.php): remove the route exposing events by unsetting it from rest_endpoints. This disables the endpoints and avoids returning protected content.
   • Block access to specific URL patterns at the firewall / webserver level:
     • Configure your WAF (or webserver) to block or require authentication for paths like:
       • /wp-json/tribe/*
       • /wp-admin/admin-ajax.php (filter requests with specific action names if feasible)
     • Rate‑limit requests to those endpoints to reduce large-scale scanning.
   • Enforce cookie/authorization checks in front-end requests:
     • Only allow requests that include a logged‑in WordPress cookie or a valid nonce header to those endpoints (if your workflow supports it).
   • Temporarily set event posts you want private to “Private” rather than “Password protected”, which requires an account with publish rights to view. This is heavier and may affect user experience but is safer short term.
3. Increase monitoring:
   • Enable logging for REST and AJAX endpoints so you can track requests to event APIs.
   • Alert on unusual spikes of unauthenticated access to those endpoints.
4. Scan your site for sensitive disclosure:
   • Use your malware and content scanner to search for recently accessed or exported event content.
   • If you host attendee info or emails, treat it as potentially exposed and follow your data breach policy.

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Practical temporary code mitigations (safe, defensive)

Below are sample defensive snippets you can use as temporary measures. Place these in a small must‑use plugin (mu‑plugin) or in theme functions only on a staging copy first, then carefully roll out to production.

Important: these snippets are defensive and intended to reduce exposure. They do not replace updating the plugin.

1) Disable REST endpoints exposing event data

<?php
/**
 * MU plugin: Disable The Events Calendar REST endpoints
 */

add_filter( 'rest_endpoints', function( $endpoints ) {
    foreach ( $endpoints as $route => $handlers ) {
        if ( strpos( $route, '/tribe/' ) !== false || strpos( $route, '/tribe/events' ) !== false ) {
            unset( $endpoints[ $route ] );
        }
    }
    return $endpoints;
});

This completely disables any REST routes that contain “tribe”. It is blunt (it may break integrations), but it is effective as a temporary mitigation.

2) Enforce authentication for tribe REST requests

<?php
/**
 * MU plugin: Require authentication for select tribe endpoints
 */

add_action( 'rest_api_init', function() {
    $routes_to_guard = [
        '/tribe/events/v1/events',
        '/tribe/events/v1/events/(?P<id>[\d]+)',
        // add other route patterns you want to protect
    ];

    foreach ( $routes_to_guard as $route ) {
        register_rest_route( 'tribe/events/v1', $route, [
            'methods'             => 'GET',
            'permission_callback' => function() {
                return is_user_logged_in();
            },
            'callback'            => function() {
                return new WP_Error( 'rest_forbidden', 'You must be authenticated to access this endpoint', [ 'status' => 403 ] );
            },
        ] );
    }
}, 1 );

This registers guarded routes that will only allow logged‑in users to proceed. Adjust route patterns as needed. Note: this strategy may require careful route naming and testing.

3) Block suspicious anonymous requests with .htaccess / nginx (server layer)

Apache (.htaccess) example to block requests to REST tribe routes:

# Block direct access to tribe REST endpoints for non-logged-in users
<IfModule mod_rewrite.c>
 RewriteEngine On
 RewriteCond %{REQUEST_URI} ^/wp-json/tribe/ [NC]
 RewriteCond %{HTTP:Cookie} !wordpress_logged_in_ [NC]
 RewriteRule .* - [F]
</IfModule>

nginx example (in server block):

location ~* ^/wp-json/tribe/ {
    if ($http_cookie !~* "wordpress_logged_in_") {
        return 403;
    }
}

These server layer rules deny unauthenticated visitors from hitting plugin REST paths. They are straightforward and effective short‑term.

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WAF / virtual patch guidance

If you manage a Web Application Firewall (WAF) — whether self‑hosted mod_security rules or a managed firewall — consider creating virtual patch rules that:

• Block or rate limit unauthenticated requests to REST endpoints that contain plugin-specific patterns such as /wp-json/tribe/ or requests with action=*tribe* to admin-ajax.
• Block requests that request full post content for password‑protected post IDs unless the request includes the expected WordPress cookie or a valid nonce.
• Detect anomalous scanning behavior: many requests for different post IDs in quick succession to the same endpoints.

Example ModSecurity signature (illustrative and must be adapted and tested in your environment):

SecRule REQUEST_URI "@beginsWith /wp-json/tribe/" "id:100001,phase:1,log,deny,status:403,msg:'Block possible Events Calendar unauthenticated REST access',chain"
  SecRule REQUEST_HEADERS:Cookie "!@contains wordpress_logged_in_" "t:none"

NOTE: Always test WAF rules on staging; misconfigured rules can block legitimate traffic and integrations.

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How to tell if your content was exposed (Indicators of Compromise)

• Access logs show unauthenticated GET/POST requests to /wp-json/tribe/ endpoints or to admin-ajax.php with hoạt động containing ‘tribe’ or ‘events’.
• Requests containing event post IDs that correspond to password‑protected posts.
• Spikes of requests to event routes originating from single IP ranges or known scanning services.
• Users report receiving event invites or participant lists they shouldn’t have seen.
• Unexpected indexes or copies of event content appearing on third‑party sites (search for unique event phrases).

If you detect these, prioritize the update and treat the content as potentially disclosed. Notify affected parties if personal data was exposed and follow your incident response and legal obligations.

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If you believe you were compromised — a practical incident response checklist

1. Immediately update The Events Calendar to 6.15.3.
2. Block the vulnerable endpoints (as per the code and WAF guidance above) to stop further exposure.
3. Review access logs for the timeframe of potential exposure and collect logs for forensic review.
4. Identify which events/posts were password‑protected and consider those items compromised.
5. If attendee emails, phone numbers or other PII were stored and possibly exposed, follow your organization’s breach notification procedures and legal obligations.
6. Rotate any relevant credentials (API keys, tokens) that might be linked to event integrations.
7. Run a full malware and file integrity scan to ensure no secondary compromise occurred.
8. Restore from a known clean backup if you find evidence of server compromise beyond the data disclosure.
9. Harden monitoring and set up alerts for suspicious REST/AJAX activity moving forward.

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Long‑term security practices (reduce exposure to similar issues)

1. Maintain an inventory of plugins and themes; track versions and update windows.
2. Enable automatic updates for security patches where safe.
3. Use a layered defense model:
   • Harden WordPress (strong passwords, 2FA for privileged users).
   • Use a WAF with custom rule capability to deploy virtual patches for plugin vulnerabilities quickly.
   • Keep server and PHP versions up to date.
4. Limit the use of public, unauthenticated APIs unless necessary.
5. Use staging sites for updates; test plugin updates for compatibility.
6. Log and monitor REST and admin‑ajax traffic, and alert on anomalous patterns.
7. Train content editors about data classification (what is sensitive and should not rely solely on post passwords).
8. Favor role‑based access and private content features instead of post passwords for more sensitive material.
9. Periodically audit plugins for security history and active maintenance. Prefer actively maintained projects where possible.
10. Use a vulnerability management process: track advisories for your installed plugins and schedule patch windows.

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Why a WAF and virtual patching matter (real world perspective)

Plugin vulnerabilities are discovered regularly. There will always be a window between disclosure and the time every site owner updates. A managed firewall that can apply virtual patches (server-side rules that block the vulnerable behavior) shortens that window and reduces the attack surface while you test and deploy official updates.

Well‑crafted virtual patches avoid breaking legitimate traffic, are reversible, and buy time for controlled testing and safe deployment of the fixed plugin version. Combine virtual patching with robust logging and vulnerability scanning to stay ahead.

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Common questions from site owners

Q: If I update immediately, do I still need to do anything else?
A: Updating to 6.15.3 removes the specific bug. After updating, review logs for previous suspicious activity, run a full site scan, and ensure no other issues exist. If you had content that may have been exposed, follow incident response steps.

Q: Are password‑protected posts still secure going forward?
A: Password protection is a convenience feature, not a substitute for access controls. When confidentiality is essential, consider using private posts (which require accounts with appropriate roles) or a membership plugin that enforces authentication robustly.

Q: Will disabling REST endpoints break my site?
A: It depends. If you or integrations rely on plugin REST routes (for front-end apps, mobile apps or third-party services), disabling them may break functionality. Use server‑side blocking or rate limiting targeted at anonymous access as a lower impact alternative while testing.

Q: Can my site be fully protected without a WAF?
A: You can reduce exposure via updates, hardening, and blocking at the webserver level; however, a WAF provides faster and more flexible mitigation capabilities, especially during zero‑day windows where you cannot update immediately.

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Technical detection rules for logging and SIEM

If you operate a SIEM or centralized logging, add these detection patterns:

• Patterns to alert:
  • Frequent hits to /wp-json/tribe/ from same IP range.
  • admin-ajax.php requests with hoạt động parameter containing tribe hoặc events and no authenticated cookie.
  • Requests to REST endpoints that returned a 200 with JSON containing post_content for known password‑protected post IDs.

Example Kibana/Elastic query:

(request.uri: "/wp-json/tribe/*" OR request.uri: "/wp-admin/admin-ajax.php") AND NOT request.headers.cookie:/wordpress_logged_in_/

Setting these alerts helps detect both mass scanning and targeted exfiltration attempts.

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What WP‑Firewall is doing and how we help

At WP‑Firewall we monitor disclosures for widely deployed WordPress plugins and translate vendor fixes into protective rules that can be applied at the firewall layer immediately. Our approach includes:

• Rapid detection and classification of plugin vulnerabilities.
• Creation and testing of virtual patches that block the vulnerable behavior without affecting legitimate traffic.
• Alerts and automated remediation options for clients with managed plans.
• Integration with logging to provide detection signatures and make forensic review simpler.

For site owners who prefer to minimize the exposure window, virtual patching and managed firewall policies provide a pragmatic, effective layer of defense while you schedule plugin updates and tests.

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A short guide to prioritizing plugin updates in your environment

• Critical/High severity: Patch immediately or apply WAF virtual patching.
• Medium: Evaluate exposure and exploitability; schedule update within 24–72 hours, with virtual patch if needed.
• Low: Schedule during your next maintenance window, but monitor for exploration in logs.

This vulnerability falls into the medium/low practical risk in many environments (CVSS ~5.3) but has broader impact for sites relying on password‑protected events. Prioritize based on whether you use password protection for content and whether those posts contain PII.

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Final recommendations (step-by-step)

1. Verify plugin version now.
2. If you run The Events Calendar <= 6.15.2, upgrade to 6.15.3 as soon as possible.
3. If you cannot upgrade immediately:
   • Implement server/WAF rules blocking unauthenticated access to tribe REST routes.
   • Consider temporarily disabling REST endpoints as shown in the defensive snippets.
   • Increase logging and monitoring of event endpoints.
4. Audit any password‑protected events for sensitive content and assume exposed until proven otherwise.
5. Follow the incident response checklist if you find evidence of access.
6. Implement the long‑term practices described above and add vulnerability monitoring to your update process.

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Closing thoughts

Vulnerabilities that result in information disclosure are often underestimated because they do not immediately result in account takeovers or remote code execution. Yet the cost of exposing private event details, attendee lists, or internal links can be substantial: reputational harm, leaked PII, or targeted follow‑on attacks.

A layered approach — timely updates, responsible staging and testing, careful use of WordPress privacy features, and a managed firewall capable of virtual patching — provides the best protection with the least disruption.

If you need help assessing exposure on your site, implementing the temporary mitigations above, or setting up a protective policy that buys you time for safe testing and updates, WP‑Firewall offers both self‑service tools and managed options to suit your needs.