CVE-2026-1915: Simple Plyr WordPress Plugin XSS Flaw

CVE-2026-1915 Overview

The Simple Plyr plugin for WordPress contains a Stored Cross-Site Scripting (XSS) vulnerability in the poster parameter within the plyr shortcode. This security flaw exists in all versions up to and including 0.0.1 due to insufficient input sanitization and output escaping on user-supplied attributes. Authenticated attackers with Contributor-level access or higher can exploit this vulnerability to inject arbitrary web scripts into WordPress pages, which execute whenever users access the compromised content.

Critical Impact

Authenticated attackers can inject persistent malicious scripts that execute in victim browsers, potentially leading to session hijacking, credential theft, defacement, or malware distribution to site visitors.

Affected Products

• Simple Plyr WordPress Plugin version 0.0.1 and earlier
• WordPress sites using the vulnerable plyr shortcode functionality
• Any WordPress installation with Contributor-level users or above using the plugin

Discovery Timeline

• 2026-02-14 - CVE CVE-2026-1915 published to NVD
• 2026-02-18 - Last updated in NVD database

Technical Details for CVE-2026-1915

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The flaw resides in the shortcode handler within simple-plyr.php where the poster parameter is processed without adequate sanitization or output escaping.

When a user with Contributor-level privileges creates or edits a post containing the plyr shortcode, they can supply malicious JavaScript code through the poster attribute. Because the plugin fails to properly sanitize this input before rendering it in the HTML output, the injected script persists in the database and executes in the browsers of all users who subsequently view the affected page.

The network-accessible attack vector combined with low attack complexity makes this vulnerability relatively easy to exploit once an attacker has obtained Contributor-level credentials. The scope is changed, meaning the vulnerability can impact resources beyond the vulnerable component itself—specifically, victim user sessions and browser contexts.

Root Cause

The root cause is insufficient input sanitization and output escaping in the shortcode processing function located at line 38 of simple-plyr.php. The plugin directly renders user-supplied attribute values into HTML output without using WordPress sanitization functions such as esc_attr(), esc_html(), or wp_kses(). This allows special characters and HTML/JavaScript code to pass through unfiltered.

Attack Vector

An attacker requires authenticated access to the WordPress site with at least Contributor-level privileges. The attack is executed through the following steps:

1. The attacker creates or edits a post using the WordPress editor
2. They insert a plyr shortcode with a malicious poster parameter containing JavaScript payload
3. When the post is published or previewed, the malicious script is stored in the database
4. Any user (including administrators) who views the page triggers execution of the injected script
5. The script can steal session cookies, redirect users, modify page content, or perform actions on behalf of the victim

The vulnerability enables persistent XSS attacks, meaning the malicious payload remains stored on the server and affects multiple victims over time. This is more dangerous than reflected XSS because it doesn't require social engineering to get victims to click a malicious link.

Detection Methods for CVE-2026-1915

Indicators of Compromise

• Unusual or obfuscated JavaScript code appearing in post content containing plyr shortcodes
• Unexpected values in the poster attribute of plyr shortcodes containing script tags or event handlers
• Reports from users experiencing unexpected behavior such as redirects or pop-ups when viewing specific pages
• Web application firewall logs showing XSS patterns in POST requests to WordPress content endpoints

Detection Strategies

• Implement content security policies (CSP) that can help detect and block inline script execution
• Review WordPress post content database for plyr shortcodes containing suspicious patterns like <script>, onerror=, onload=, or javascript:
• Deploy web application firewall rules to monitor for XSS payloads in shortcode attributes
• Enable and review WordPress audit logging for content modifications by Contributor-level users

Monitoring Recommendations

• Configure alerts for unusual JavaScript patterns in database content tables
• Monitor browser console errors on the client side that may indicate blocked XSS attempts
• Review access logs for patterns suggesting exploitation attempts against shortcode endpoints
• Implement integrity monitoring on plugin files to detect unauthorized modifications

How to Mitigate CVE-2026-1915

Immediate Actions Required

• Deactivate the Simple Plyr plugin until a patched version is available
• Audit existing WordPress posts for potentially malicious content in plyr shortcodes
• Review user accounts with Contributor-level access or above for unauthorized access
• Implement a Web Application Firewall (WAF) with XSS protection rules

Patch Information

At the time of this advisory, no official patch has been released for the Simple Plyr plugin. Organizations should monitor the WordPress Plugin Repository and Wordfence Vulnerability Analysis for updates regarding security patches.

Workarounds

• Remove the Simple Plyr plugin entirely and use an alternative media player plugin with proper security controls
• Restrict Contributor-level access to only trusted users until the vulnerability is patched
• Implement server-side input validation using WordPress hooks to sanitize shortcode attributes
• Deploy Content Security Policy headers to mitigate the impact of successful XSS attacks by restricting script execution sources

# Example: Add Content Security Policy header in Apache .htaccess
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none';"

# Example: Add CSP header in Nginx configuration
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none';";