CVE-2025-23434: Easy EU Cookie Law Stored XSS Vulnerability

CVE-2025-23434 Overview

CVE-2025-23434 is a stored Cross-Site Scripting (XSS) vulnerability in the Easy EU Cookie Law WordPress plugin developed by viher3. The flaw affects all versions up to and including 1.3.3.1. The vulnerability results from improper neutralization of user-supplied input during web page generation, classified under [CWE-79]. An authenticated attacker with low privileges can inject malicious scripts that persist within the application. These scripts execute in the browser of any user who loads the affected page.

Critical Impact
Attackers with low-privileged access can inject persistent JavaScript payloads that execute in visitors' browsers, enabling session theft, credential harvesting, and administrative account takeover through user interaction.

Affected Products

viher3 Easy EU Cookie Law WordPress plugin
All versions from initial release through 1.3.3.1
WordPress installations running the vulnerable plugin

Discovery Timeline

2025-01-16 - CVE-2025-23434 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-23434

Vulnerability Analysis

The Easy EU Cookie Law plugin fails to properly sanitize and encode user-supplied input before rendering it within HTML output. This allows an authenticated attacker to store arbitrary JavaScript payloads in the plugin's configuration or content fields. When another user visits a page containing the injected payload, the browser executes the malicious script in the site's origin context.

Stored XSS is more impactful than reflected variants because the payload persists on the server. Every visitor to the affected page becomes a potential victim without requiring social engineering. The Patchstack advisory tracks this issue as a scope-changing vulnerability, meaning the exploit affects resources beyond the vulnerable component.

Root Cause

The root cause is the absence of output encoding and input validation on fields exposed by the plugin's administrative interface. WordPress provides functions such as esc_html(), esc_attr(), and wp_kses() for safe output rendering, but the affected plugin does not consistently apply these to user-controlled data prior to version 1.3.3.1.

Attack Vector

Exploitation requires network access to the WordPress site and low-privileged authenticated access to the plugin's configuration interface. The attacker submits a crafted payload containing HTML or JavaScript. User interaction is required to trigger the payload, which then executes within the victim's session. Refer to the Patchstack XSS Vulnerability Advisory for technical specifics.

Detection Methods for CVE-2025-23434

Indicators of Compromise

Unexpected <script> tags or event handlers such as onerror, onload, or onmouseover appearing in plugin configuration values stored in the WordPress database.
Outbound HTTP requests from administrator browsers to unfamiliar domains after visiting pages rendered by the plugin.
New or modified administrator accounts created shortly after an administrator session interacted with plugin-controlled content.

Detection Strategies

Review the wp_options and plugin-specific tables for entries containing HTML tags, JavaScript keywords, or encoded payloads such as %3Cscript%3E.
Inspect web server access logs for POST requests to the plugin's administrative endpoints followed by anomalous GET requests from privileged users.
Deploy Content Security Policy (CSP) reporting to identify script-source violations originating from injected payloads.

Monitoring Recommendations

Monitor WordPress audit logs for changes to plugin settings by users with contributor or higher roles.
Alert on creation of new administrator accounts or modifications to existing user roles following plugin interaction.
Correlate browser telemetry from administrator endpoints against WordPress admin activity to detect session hijacking attempts.

How to Mitigate CVE-2025-23434

Immediate Actions Required

Identify all WordPress instances running the Easy EU Cookie Law plugin at version 1.3.3.1 or earlier.
Deactivate the plugin until a patched version is confirmed installed if the site processes sensitive administrator sessions.
Audit plugin configuration values and stored content for existing injected payloads and remove them.
Rotate credentials and invalidate active sessions for administrator accounts that accessed affected pages.

Patch Information

Consult the Patchstack XSS Vulnerability Advisory for patched version guidance. Upgrade to a version later than 1.3.3.1 when available from the plugin vendor. If no patched release exists, plan for removal or replacement of the plugin.

Workarounds

Restrict access to the WordPress administrative interface using IP allowlists or a web application firewall (WAF).
Deploy a strict Content Security Policy that disallows inline scripts and unknown script sources to limit payload execution.
Enforce least-privilege role assignments so that only trusted administrators can modify plugin configuration.
Apply virtual patching rules through a WAF to filter requests containing <script> tags or common XSS vectors targeting the plugin's endpoints.

bash

# Example WAF rule (ModSecurity) to block XSS payloads targeting plugin endpoints
SecRule REQUEST_URI "@contains /wp-admin/admin.php?page=easy-eu-cookie-law" \
  "id:1002345,phase:2,deny,status:403,\
   chain,msg:'Potential XSS payload targeting Easy EU Cookie Law plugin'"
  SecRule ARGS "@rx (?i)(<script|onerror=|onload=|javascript:)" "t:none,t:urlDecodeUni"