CVE-2026-1825: Show YouTube Video WordPress Plugin XSS Flaw

CVE-2026-1825 Overview

The Show YouTube Video plugin for WordPress contains a Stored Cross-Site Scripting (XSS) vulnerability in the plugin's syv shortcode. All versions up to and including 1.1 are affected due to insufficient input sanitization and output escaping on user-supplied attributes. This vulnerability allows authenticated attackers with contributor-level access or above to inject arbitrary web scripts into WordPress pages that execute whenever a user accesses an injected page.

Critical Impact

Authenticated attackers can inject malicious JavaScript that persists in the database and executes in the browsers of site visitors, potentially leading to session hijacking, credential theft, or malware distribution.

Affected Products

• Show YouTube Video plugin for WordPress version 1.1 and earlier
• WordPress installations using the vulnerable syv shortcode functionality

Discovery Timeline

• 2026-03-07 - CVE-2026-1825 published to NVD
• 2026-03-09 - Last updated in NVD database

Technical Details for CVE-2026-1825

Vulnerability Analysis

This Stored Cross-Site Scripting vulnerability stems from improper handling of user-supplied input within the syv shortcode implementation. When contributors or higher-privileged users create or edit posts containing the shortcode, the plugin fails to properly sanitize attribute values before storing them in the database and subsequently rendering them in the page output.

The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation). The attack can be executed remotely over the network without requiring user interaction once the malicious content is stored. The scope is changed, meaning the vulnerable component (the plugin) can affect resources beyond its security scope (the user's browser session).

Root Cause

The root cause lies in the show-youtube-video.php file where the shortcode handler processes user-supplied attributes without adequate sanitization. According to the WordPress Plugin source code at line 29 and line 79, the plugin directly incorporates attribute values into HTML output without escaping special characters, allowing script injection.

The vulnerability affects the shortcode's attribute handling where values are passed directly to the rendered output. WordPress provides functions like esc_attr() and wp_kses() specifically to prevent such issues, but these appear to be missing or improperly implemented in the affected code paths.

Attack Vector

The attack requires an attacker to have at least contributor-level access to the WordPress site. Once authenticated, the attacker can craft a malicious shortcode with JavaScript payload embedded in the shortcode attributes. When the post is published or previewed, the injected script executes in the context of any user viewing the page.

A typical attack scenario involves embedding event handlers or script tags within shortcode attributes that bypass the plugin's input validation. Since the malicious script is stored in the database, it persists and executes for every visitor who views the affected page, making this a Stored XSS vulnerability with broader impact than reflected XSS variants.

Detection Methods for CVE-2026-1825

Indicators of Compromise

• Unexpected JavaScript code or HTML event handlers within syv shortcode attributes in post content
• Anomalous script execution reported by client-side security tools when viewing WordPress pages
• Database entries in wp_posts table containing suspicious shortcode patterns with encoded or obfuscated script payloads
• User reports of unexpected browser behavior or security warnings when visiting specific pages

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect XSS patterns in POST requests to WordPress admin endpoints
• Enable Content Security Policy (CSP) headers to restrict inline script execution and receive violation reports
• Deploy database monitoring to alert on suspicious patterns being inserted into post content fields
• Utilize WordPress security plugins that scan shortcode attributes for malicious content

Monitoring Recommendations

• Monitor WordPress admin access logs for contributor and author activity patterns that include bulk post editing
• Configure browser-based XSS auditing and CSP violation reporting to centralized logging infrastructure
• Implement regular automated scans of post content for known XSS payload signatures
• Review user account activity for newly created contributors or unusual authentication patterns

How to Mitigate CVE-2026-1825

Immediate Actions Required

• Deactivate and remove the Show YouTube Video plugin from all WordPress installations until a patched version is available
• Audit existing posts for malicious shortcode content by searching the database for suspicious syv shortcode entries
• Review and limit contributor-level access to only trusted users
• Implement a Content Security Policy header to mitigate the impact of any existing injected scripts

Patch Information

At the time of publication, review the Wordfence vulnerability report for the latest patch status and remediation guidance. Site administrators should monitor the WordPress plugin repository for an updated version that addresses this vulnerability. Until a patch is available, removing the plugin entirely is the recommended course of action.

Workarounds

• Remove the Show YouTube Video plugin and use alternative YouTube embedding methods such as WordPress's native embed functionality
• If the plugin must remain active, restrict post creation and editing to administrator accounts only
• Implement server-side input filtering using .htaccess or nginx rules to block common XSS payloads
• Deploy a WordPress security plugin with real-time XSS detection capabilities to provide an additional layer of protection

# Search WordPress database for potentially malicious syv shortcode entries
wp db query "SELECT ID, post_title FROM wp_posts WHERE post_content LIKE '%[syv%script%' OR post_content LIKE '%[syv%onerror%' OR post_content LIKE '%[syv%onclick%';"

# Deactivate the vulnerable plugin via WP-CLI
wp plugin deactivate show-youtube-video

# Optionally remove the plugin entirely
wp plugin delete show-youtube-video