CVE-2025-47500 Overview
CVE-2025-47500 is a stored Cross-Site Scripting (XSS) vulnerability in the Stackable Ultimate Gutenberg Blocks plugin for WordPress, developed by Benjamin Intal. The flaw stems from improper neutralization of user-supplied input during web page generation [CWE-79]. Affected versions include Stackable releases up to and including 3.19.5. An authenticated attacker with high privileges can inject malicious script content that executes in the browser of any visitor who renders the affected page. Exploitation requires user interaction and crosses a security boundary, enabling impact on confidentiality, integrity, and availability of the WordPress site.
Critical Impact
Authenticated attackers can store malicious JavaScript that executes in visitors' browsers, enabling session theft, content tampering, and redirection attacks against WordPress sites running vulnerable Stackable versions.
Affected Products
- Benjamin Intal Stackable (stackable-ultimate-gutenberg-blocks) WordPress plugin
- All versions from initial release through 3.19.5
- WordPress sites using vulnerable Stackable block configurations
Discovery Timeline
- 2026-01-22 - CVE-2025-47500 published to NVD
- 2026-04-27 - Last updated in NVD database
Technical Details for CVE-2025-47500
Vulnerability Analysis
The vulnerability resides in the Stackable Ultimate Gutenberg Blocks plugin, which extends the WordPress block editor with additional content blocks. The plugin fails to properly sanitize or encode user-supplied input before rendering it within generated web pages. This allows an attacker with editor-level or higher privileges to inject arbitrary HTML and JavaScript into block attributes or content fields.
Once stored in the WordPress database, the malicious payload executes whenever a user views the affected post or page. Because the script runs in the context of the site's origin, attackers can hijack administrator sessions, perform actions on behalf of authenticated users, or exfiltrate sensitive information rendered in the page.
Root Cause
The root cause is missing or insufficient output encoding when block content is serialized into the final HTML response. The plugin trusts authenticated input fields and renders them without escaping HTML entities or stripping unsafe attributes. This is a classic stored XSS pattern in WordPress block plugins that handle rich content.
Attack Vector
Exploitation requires network access to the WordPress administrative interface and authenticated access with elevated privileges. The attacker crafts a block configuration containing JavaScript payloads in vulnerable fields, saves the post, and waits for a victim to render the page. Successful exploitation results in script execution under the victim's session.
No verified proof-of-concept code is publicly available. For technical details, see the Patchstack WordPress Plugin Vulnerability advisory.
Detection Methods for CVE-2025-47500
Indicators of Compromise
- Unexpected <script> tags, javascript: URIs, or inline event handlers (onerror, onload, onclick) stored in wp_posts content for Stackable blocks
- Outbound HTTP requests from visitor browsers to attacker-controlled domains after rendering affected pages
- Anomalous administrator session activity originating shortly after pages with Stackable blocks were viewed
- WordPress audit log entries showing post edits by lower-privileged accounts that include block markup
Detection Strategies
- Query the WordPress database for post content matching patterns such as wp:stackable/* blocks containing <script, onerror=, or encoded JavaScript payloads
- Deploy a web application firewall rule to inspect outbound HTML responses for script content within Stackable block wrappers
- Compare installed plugin version against 3.19.5 across managed WordPress sites and flag vulnerable installations
Monitoring Recommendations
- Enable verbose WordPress audit logging for post creation and modification events involving Stackable blocks
- Monitor administrator account behavior for unusual API calls or privilege changes following page views
- Alert on Content Security Policy (CSP) violation reports referencing inline script execution on affected pages
How to Mitigate CVE-2025-47500
Immediate Actions Required
- Update the Stackable Ultimate Gutenberg Blocks plugin to a version released after 3.19.5 once the vendor publishes a fix
- Audit all existing posts and pages containing Stackable blocks for stored script content and remove malicious payloads
- Review WordPress user accounts and revoke editor or higher privileges that are no longer required
Patch Information
At the time of publication, the vulnerability affects all versions through 3.19.5. Administrators should consult the Patchstack advisory for the latest patched version information and apply updates through the WordPress plugin manager.
Workarounds
- Temporarily deactivate the Stackable plugin on sites that cannot be patched immediately
- Enforce a strict Content Security Policy that disallows inline scripts and restricts script sources to trusted origins
- Restrict editor-level access to a minimal set of trusted administrators until a fix is applied
- Deploy a WordPress-aware web application firewall with virtual patching rules for Stackable XSS payloads
# Example: enforce a restrictive Content Security Policy via .htaccess
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self'; frame-ancestors 'self'"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
