CVE-2025-15489: Passster WordPress Plugin Disclosure Flaw

CVE-2025-15489 is an information disclosure vulnerability in Passster WordPress plugin that allows unauthenticated attackers to bypass password protection and retrieve protected content through improper AJAX handling. This post explains its technical details, affected versions, impact, and mitigation steps.

CVE-2025-15489 Overview

CVE-2025-15489 affects the Passster WordPress plugin in versions before 4.2.24. The plugin fails to properly handle input within an AJAX action, allowing unauthenticated attackers to retrieve the value of password-protected content. The flaw is categorized under [CWE-863] Incorrect Authorization and exposes content that site administrators intended to restrict behind a password gate.

Critical Impact
Unauthenticated remote attackers can bypass the plugin's password protection and read protected content directly over the network without user interaction.

Affected Products

Passster WordPress plugin versions prior to 4.2.24

Discovery Timeline

2026-09-02 - CVE-2025-15489 published to NVD
2026-09-02 - Last updated in NVD database

Technical Details for CVE-2025-15489

Vulnerability Analysis

The Passster plugin provides password-based access control for individual WordPress pages, posts, or content sections. Site owners configure a password, and visitors must submit it to view the protected material. CVE-2025-15489 breaks that trust boundary.

The plugin exposes an AJAX action that does not properly validate authorization before returning protected data. An unauthenticated attacker can invoke the action and receive the value of password-protected content in the response, without ever submitting the correct password. This is an authorization flaw, not an authentication bypass in the traditional sense: the endpoint returns data that should have been gated on a successful password check.

Root Cause

The root cause is improper handling of request input inside an AJAX handler combined with missing authorization checks, consistent with [CWE-863] Incorrect Authorization. The handler processes the request and returns protected content based on client-supplied parameters, without confirming that the caller has satisfied the password requirement bound to that content.

Attack Vector

The attack is network-based and requires no privileges or user interaction. An attacker sends a crafted HTTP POST request to wp-admin/admin-ajax.php targeting the vulnerable Passster AJAX action. The server responds with the protected content value. See the WPScan Vulnerability Report for additional technical context.

No verified public exploit code is available at the time of publication.
See the WPScan advisory for technical details.

Detection Methods for CVE-2025-15489

Indicators of Compromise

Unauthenticated POST requests to /wp-admin/admin-ajax.php referencing Passster plugin AJAX actions from external IP addresses.
Repeated AJAX calls from a single source enumerating content identifiers such as post IDs or area keys.
Access log entries returning HTTP 200 responses with content payloads to callers that never submitted the Passster password form.

Detection Strategies

Inspect web server and WordPress access logs for anomalous access patterns targeting Passster AJAX endpoints without a preceding password submission.
Correlate AJAX request bursts with reads of protected posts or pages to identify enumeration behavior.
Deploy a WordPress-aware Web Application Firewall (WAF) rule that flags Passster AJAX actions invoked without an authenticated session or valid nonce.

Monitoring Recommendations

Alert on outbound response sizes from admin-ajax.php that exceed expected baselines for the Passster action.
Monitor for the installed Passster version across WordPress fleets and flag any instance running below 4.2.24.
Track user-agent and IP diversity hitting Passster AJAX endpoints to detect scripted scanning activity.

How to Mitigate CVE-2025-15489

Immediate Actions Required

Update the Passster plugin to version 4.2.24 or later on every WordPress site where it is installed.
Rotate any passwords configured within Passster, as protected values may already have been exposed.
Audit access logs since deployment of vulnerable versions to identify unauthorized retrieval of protected content.

Patch Information

The vendor has resolved this issue in Passster version 4.2.24. Administrators should upgrade through the WordPress plugin manager or by replacing plugin files with the fixed release. Refer to the WPScan Vulnerability Report for advisory details.

Workarounds

If patching cannot be applied immediately, deactivate the Passster plugin and remove reliance on plugin-based password gating for sensitive content.
Restrict access to wp-admin/admin-ajax.php for unauthenticated users at the WAF level, allowing only known-safe actions.
Relocate highly sensitive material out of Passster-protected containers until the update is deployed.

bash

# Update Passster via WP-CLI
wp plugin update passster --version=4.2.24
wp plugin list --name=passster --fields=name,status,version