A critical Cross-Site Scripting (XSS) vulnerability has been identified in the Fast WP Speed plugin. This vulnerability could allow a malicious actor to inject malicious scripts into the website, which could then be executed by visitors to the site.

LEE SE HYOUNG (hackintoanetwork) discovered and reported this vulnerability.

This vulnerability has not been fixed yet. It is important to note that disabling the plugin may break some functionality on your website. User should consider switching to a different plugin or developing their own solution.


High (CVSS 3.1 score of 7.1)

Affected Versions

All versions of the Fast WP Speed plugin


If a malicious actor is able to exploit this vulnerability, they could:

  • Inject malicious scripts into the website, which could then be executed by visitors to the site.
  • Redirect visitors to malicious websites
  • Inject advertisements into the website
  • Steal cookies or other sensitive information from visitors


Given the high severity of this vulnerability, it is critical to take immediate action:

  1. Temporary Deactivation: Until a patched version becomes available, consider temporarily deactivating the Fast WP Speed Plugin. This precautionary measure can reduce the risk of exploitation until a fixed version is released.
  2. Plugin Updates: Monitor updates for the Fast WP Speed Plugin closely. As soon as a new version is made available with a patch for this vulnerability, update the plugin to the latest version.
  3. Security Audit: After applying updates, conduct a thorough security audit on the WordPress website to ensure that the vulnerability has been successfully addressed.
  4. Monitoring and Scanning: Regularly monitor your website for unusual activities and conduct security scans to identify any potential issues.
  5. Stay Informed: Keep abreast of the latest developments regarding the Fast WP Speed Plugin, including updates on the vulnerability and the release of a patched version.