CVE-2025-39363 Overview
CVE-2025-39363 is a stored cross-site scripting (XSS) vulnerability [CWE-79] in the AlphaEfficiencyTeam Custom Login and Registration WordPress plugin. The flaw stems from improper neutralization of user-supplied input during web page generation. An authenticated attacker with low privileges can inject persistent JavaScript payloads that execute in the browser of any user who views the affected page. The issue affects all versions up to and including 1.0.0, with no patched version listed at the time of publication.
Critical Impact
Authenticated attackers can inject stored JavaScript that executes in visitors' and administrators' browsers, enabling session theft, credential harvesting, and administrative account takeover through follow-on actions.
Affected Products
- AlphaEfficiencyTeam Custom Login and Registration plugin for WordPress
- All versions from n/a through 1.0.0
- WordPress sites with the plugin installed and active
Discovery Timeline
- 2025-05-05 - CVE-2025-39363 published to the National Vulnerability Database (NVD)
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-39363
Vulnerability Analysis
The vulnerability is a stored cross-site scripting flaw in the Custom Login and Registration plugin. The plugin fails to sanitize or escape user-controlled input before persisting it and rendering it back into HTML output. An attacker submits crafted input containing HTML or JavaScript through an exposed plugin field. The payload is stored server-side and served to any user who loads the affected view.
Exploitation requires low privileges and user interaction, according to the CVSS vector. The scope change indicator means the injected script executes in a security context different from the vulnerable component, typically the authenticated browser session of a WordPress administrator. Successful exploitation can lead to session hijacking, forced administrative actions, phishing overlays, or pivoting to full site compromise via WordPress admin functionality.
Root Cause
The root cause is missing input neutralization on data written to web pages generated by the plugin. Input that should be escaped with WordPress helpers such as esc_html(), esc_attr(), or wp_kses() is instead rendered verbatim. This allows <script> tags and event-handler attributes to survive into the DOM.
Attack Vector
The attack vector is network-based and requires an authenticated user with low privileges. The attacker submits a malicious payload through a plugin-controlled input field. When an administrator or another user renders the stored content, the payload executes with that user's privileges in the site's origin. See the Patchstack XSS Vulnerability Report for advisory details.
No verified public proof-of-concept code is available. The vulnerability mechanism follows the standard stored XSS pattern: unfiltered input persisted to the database and reflected into HTML output without escaping.
Detection Methods for CVE-2025-39363
Indicators of Compromise
- Unexpected <script>, <iframe>, or on*= event handler strings stored in plugin-related WordPress database tables such as wp_usermeta or wp_options.
- Outbound requests from administrator browsers to unfamiliar domains shortly after loading plugin-managed pages.
- New administrative users, altered user roles, or modified plugin/theme files without a corresponding admin action in audit logs.
Detection Strategies
- Review web server access logs for POST requests to plugin endpoints containing URL-encoded <script>, javascript:, or onerror= patterns.
- Query the WordPress database for stored fields associated with the plugin and grep for HTML control characters and event-handler substrings.
- Deploy a web application firewall rule that flags XSS payload signatures targeting registration and profile fields.
Monitoring Recommendations
- Enable WordPress activity logging to record user registrations, profile edits, and role changes tied to the plugin.
- Alert on any privilege escalation or new administrator creation following interaction with plugin-managed pages.
- Monitor administrator browser sessions with endpoint telemetry for anomalous script execution, credential form injection, or cookie exfiltration attempts.
How to Mitigate CVE-2025-39363
Immediate Actions Required
- Deactivate and remove the Custom Login and Registration plugin until a patched version is published by the vendor.
- Audit all WordPress user accounts, focusing on recently created administrators and unexpected role changes.
- Rotate credentials and invalidate active sessions for all administrative users who may have viewed plugin-rendered pages.
Patch Information
No vendor patch is listed in the NVD entry or the Patchstack advisory at the time of publication. All versions up to and including 1.0.0 are affected. Track the Patchstack advisory for a fixed release, and subscribe to the WordPress plugin repository page for update notifications.
Workarounds
- Restrict registration functionality by disabling the plugin or blocking access to its endpoints at the web server or WAF layer.
- Apply a WAF rule set that filters XSS payloads in POST parameters submitted to plugin routes.
- Enforce a strict Content Security Policy (CSP) that disallows inline scripts and untrusted script sources to limit payload execution.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
