The Urgent Need to Remove Vulnerable Polyfill.js – Safeguard Your Website

In the rapidly evolving landscape of web development, ensuring the security and performance of your website is paramount. Recently, a significant security issue has surfaced involving Polyfill.js, a popular JavaScript library used to support older browsers. This vulnerability poses a severe risk to countless websites globally, and immediate action is necessary to protect your site from potential harm. At Pragmio, we specialize in securing and optimizing websites. Contact us today to safeguard your online presence.

Understanding the Polyfill.js Vulnerability

Polyfill.js is widely used to ensure compatibility across different browsers by emulating modern web standards in older browsers. This library has been a staple for many developers aiming to provide a consistent user experience. However, a recent development has compromised its integrity.

In February 2024, a Chinese company, Funnull, acquired the domain and associated GitHub account for Polyfill.js. This acquisition has led to the introduction of malicious code within the Polyfill.js script. Any website still loading scripts from is now at risk of downloading and executing this malicious code, potentially compromising user data and site integrity.

The Risks Involved

The modified Polyfill.js script can lead to several security issues, including:

  1. Data Breaches: Malicious code can harvest sensitive user information.
  2. Website Defacement: Unauthorized scripts can alter the content and appearance of your site.
  3. SEO Penalties: Search engines may penalize compromised sites, leading to a drop in rankings.
  4. User Trust: Visitors may lose trust in your website if their data is at risk.

Given these severe risks, it is crucial to remove or replace the Polyfill.js script from your website immediately.

Steps to Remove Polyfill.js

  1. Identify Usage: Search your website’s codebase for any instances of and Polyfill.js.
  2. Remove the Script: Delete any <script> tags referencing
  3. Test Compatibility: Ensure your website functions correctly in modern browsers without the Polyfill.js script.
  4. Use Secure Alternatives: If necessary, replace Polyfill.js with secure alternatives from reliable CDNs like Cloudflare.

Example Code to Deregister Polyfill.js in WordPress

For WordPress users, you can deregister Polyfill.js globally by adding the following code to your theme’s functions.php file:

function disable_polyfill_scripts() {
// Deregister the polyfill scripts
add_action(‘wp_enqueue_scripts’, ‘disable_polyfill_scripts’, 100);


Ensure Your Website’s Security with Pragmio

Removing Polyfill.js is a crucial step, but it requires careful execution to ensure your website remains functional and secure. At Pragmio, we offer expert assistance to help you navigate this process seamlessly. Our team specializes in web security and optimization, ensuring your site is protected from emerging threats.

By choosing Pragmio, you benefit from:

  • Expert Analysis: Comprehensive assessment of your website’s current security status.
  • Safe Script Removal: Efficient and safe removal of vulnerable scripts.
  • Alternative Solutions: Implementation of secure and reliable alternatives.
  • Continuous Support: Ongoing monitoring and support to keep your website secure.

Contact Us Today

Don’t leave your website’s security to chance. Contact Pragmio today to secure your website from the vulnerabilities associated with Polyfill.js.