CVE-2025-12033 Overview
CVE-2025-12033 is a Stored Cross-Site Scripting (XSS) vulnerability [CWE-79] in the Simple Banner WordPress plugin. The flaw exists in all versions up to and including 3.0.10. The plugin fails to properly sanitize input and escape output for the pro_version_activation_code parameter. Authenticated attackers with administrator-level access can inject arbitrary JavaScript that executes when users view affected pages. The issue only impacts WordPress multi-site installations and single-site installations where the unfiltered_html capability has been disabled.
Critical Impact
Administrators on multi-site WordPress deployments can inject persistent scripts that execute in the browsers of other users, enabling session hijacking, credential theft, or further privilege escalation across the network.
Affected Products
- Simple Banner plugin for WordPress — versions ≤ 3.0.10
- WordPress multi-site installations running the affected plugin
- WordPress single-site installations with unfiltered_html disabled
Discovery Timeline
- 2025-10-22 - CVE-2025-12033 published to the National Vulnerability Database (NVD)
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-12033
Vulnerability Analysis
The vulnerability resides in the handling of the pro_version_activation_code parameter within the Simple Banner plugin's administrative settings. The plugin accepts the parameter value and later renders it in HTML context without applying WordPress sanitization functions such as sanitize_text_field() on input or esc_attr() / esc_html() on output.
An authenticated administrator can submit a payload containing JavaScript through the activation code field. The unescaped value is then stored in the database and reflected on pages served to site users. When another user loads a page containing the injected content, the browser executes the attacker-controlled script under the site's origin.
Because the vulnerability requires administrator privileges, exploitation is meaningful primarily in contexts where administrators are not fully trusted. WordPress multi-site networks distinguish between site administrators and super administrators, and by default disable unfiltered_html for lower-tier admins to prevent exactly this class of injection.
Root Cause
The root cause is insufficient input sanitization and output escaping on the pro_version_activation_code parameter. The plugin does not enforce the WordPress security boundary that assumes non-super administrators cannot post arbitrary HTML or scripts.
Attack Vector
Exploitation requires authenticated access with administrator privileges over the network. The attacker submits the malicious payload through the plugin's settings interface. The stored script triggers whenever a victim loads a page that renders the injected value, resulting in script execution in the victim's authenticated session. Refer to the Wordfence Vulnerability Report for additional technical context.
// No verified exploit code is publicly available.
// See the Wordfence advisory linked above for further details.
Detection Methods for CVE-2025-12033
Indicators of Compromise
- Presence of <script> tags, event handlers such as onerror=, or JavaScript URIs stored in the pro_version_activation_code option within the WordPress wp_options table.
- Unexpected outbound requests from user browsers to attacker-controlled domains after loading pages that render Simple Banner content.
- Administrator account changes to the Simple Banner settings that do not correspond to a legitimate license activation.
Detection Strategies
- Query the WordPress database for the plugin's stored settings and inspect the activation code value for HTML or JavaScript content.
- Review web server access logs for POST requests to admin.php or options.php that update Simple Banner settings from unexpected accounts or IP addresses.
- Enable a Content Security Policy (CSP) in report-only mode to surface inline script execution originating from plugin-rendered pages.
Monitoring Recommendations
- Alert on modifications to Simple Banner plugin options performed by non-super administrator accounts on multi-site networks.
- Monitor for new or unexpected WordPress administrator logins, particularly those preceding plugin configuration changes.
- Track plugin version inventory to identify any WordPress instances still running Simple Banner 3.0.10 or earlier.
How to Mitigate CVE-2025-12033
Immediate Actions Required
- Update the Simple Banner plugin to a version newer than 3.0.10 on all WordPress sites where it is installed.
- Audit administrator accounts on multi-site installations and remove any unrecognized or unnecessary privileged users.
- Review the current stored value of pro_version_activation_code and remove any content containing HTML or scripts.
Patch Information
The vendor addressed the vulnerability in a plugin update tracked in the WordPress Plugin Changeset. Site owners should apply the update through the WordPress plugin manager or by installing the latest release directly from the plugin repository.
Workarounds
- Temporarily deactivate the Simple Banner plugin on multi-site installations until the patched version is deployed.
- Restrict access to the plugin's settings page using role management tools to limit exposure while a patch is pending.
- Implement a strict Content Security Policy that disallows inline scripts on WordPress admin and front-end pages.
# Example: use WP-CLI to update the plugin across a multi-site network
wp plugin update simple-banner --network
wp plugin list --name=simple-banner --fields=name,status,version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.