CVE-2025-11811 Overview
The Simple Youtube Shortcode plugin for WordPress contains a stored Cross-Site Scripting (XSS) vulnerability [CWE-79] in all versions up to and including 1.1.3. The flaw exists in the embed_youtube shortcode, which fails to properly sanitize input or escape output on the id attribute. Authenticated users with contributor-level access or higher can inject arbitrary JavaScript into WordPress pages. The injected scripts execute in the browser of any user who visits an affected page.
Critical Impact
Contributor-level accounts can persist arbitrary JavaScript into published pages, enabling session theft, credential harvesting, and administrative account takeover when higher-privileged users view the content.
Affected Products
- WordPress Simple Youtube Shortcode plugin versions up to and including 1.1.3
- WordPress sites permitting contributor-level or higher accounts
- Any site rendering pages that include the embed_youtube shortcode
Discovery Timeline
- 2025-10-22 - CVE-2025-11811 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-11811
Vulnerability Analysis
The vulnerability resides in the embed_youtube shortcode handler within simple-youtube-shortcode.php. The plugin accepts an id attribute from user-supplied shortcode input and reflects it into the rendered HTML without adequate sanitization or escaping. An authenticated attacker with contributor privileges can embed a crafted shortcode into a post or page. When the post is later viewed, the malicious payload executes in the victim's browser under the site's origin.
Because the payload is stored in the WordPress database and rendered on subsequent page loads, exploitation does not require repeated attacker interaction. The scope change in the CVSS vector indicates the injected script executes in a security context beyond the vulnerable component itself, affecting site visitors and administrators who preview or view contributor-submitted content.
Root Cause
The root cause is insufficient input sanitization and missing output escaping on the id shortcode attribute. WordPress provides functions such as esc_attr() and sanitize_text_field() for this exact scenario, but the plugin does not apply them before echoing the attribute into the HTML response. See the WordPress Plugin Code Reference for the affected code path.
Attack Vector
Exploitation requires an authenticated session with contributor-level access or higher. The attacker submits a post or page containing an embed_youtube shortcode whose id attribute carries a JavaScript payload, for example breaking out of the attribute context and injecting a <script> tag or event handler. Once an editor, administrator, or site visitor loads the page, the browser executes the payload in the site's origin. This enables session cookie theft, forced administrative actions via authenticated requests, and pivot to full site compromise. No user interaction beyond viewing the page is required.
No public proof-of-concept exploit or ExploitDB entry is listed for CVE-2025-11811. Refer to the Wordfence Vulnerability Report for additional technical context.
Detection Methods for CVE-2025-11811
Indicators of Compromise
- Post or page content containing embed_youtube shortcodes with id values that include characters such as ", <, >, script, onerror, or javascript:
- Unexpected <script> tags, inline event handlers, or external script references rendered inside YouTube embed markup
- New or modified contributor accounts creating draft or published posts that reference the plugin's shortcode
- Outbound browser requests from site visitors to unfamiliar domains sourced from post pages
Detection Strategies
- Query the wp_posts table for post_content values matching embed_youtube shortcodes and inspect the id attribute for non-alphanumeric characters outside the expected YouTube video ID pattern.
- Deploy web application firewall rules that flag shortcode attribute values containing HTML control characters or JavaScript keywords.
- Review WordPress audit logs for post creations and edits performed by contributor-role accounts referencing the plugin.
Monitoring Recommendations
- Enable content security policy (CSP) reporting to capture unexpected script execution on rendered pages.
- Monitor authentication logs for privilege escalation attempts or session token reuse across IPs following contributor logins.
- Alert on installation of vulnerable plugin versions across managed WordPress fleets using a plugin inventory scan.
How to Mitigate CVE-2025-11811
Immediate Actions Required
- Deactivate the Simple Youtube Shortcode plugin on affected WordPress installations until a patched release is available.
- Audit all posts and pages for existing embed_youtube shortcodes and remove any containing suspicious id attribute payloads.
- Rotate administrator session cookies and force password resets for any account that may have viewed injected content.
Patch Information
At the time of publication, no fixed version beyond 1.1.3 is listed in the WordPress Simple YouTube Shortcode plugin repository. Administrators should monitor the plugin page and the Wordfence Vulnerability Report for a corrected release.
Workarounds
- Restrict contributor-level and above accounts to trusted users only, and require multi-factor authentication for all authors.
- Remove or replace the plugin with an actively maintained alternative that properly escapes shortcode attributes.
- Deploy a WAF ruleset that inspects post_content on save and blocks shortcode attributes containing HTML or script syntax.
- Apply a strict Content Security Policy that disallows inline scripts and unauthorized external script sources.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
