Critical SQL Injection Vulnerability Exposes Millions of WordPress Sites Using WP Fastest Cache (CVE-2023-6063)


WordPress, powering over a third of the internet, is a popular platform for website creation and management. However, its widespread use also makes it an attractive target for cyber threats. Recently, the WPScan team from Automattic uncovered a critical security flaw in the widely-used WordPress plugin, WP Fastest Cache, potentially exposing the databases of over a million websites to unauthorized access.

The WP Fastest Cache Plugin: A Brief Overview

WP Fastest Cache, designed to enhance website performance, accelerate page loading times, and improve user experience, has become an indispensable tool for many site owners. According to statistics, this caching plugin is actively employed by more than a million websites globally. Its primary goal is to boost website rankings on search engines like Google, emphasizing the importance of its role in the digital landscape.

Unveiling the Vulnerability

Despite its widespread use, recent download statistics from reveal that over 600,000 websites still operate on versions of WP Fastest Cache susceptible to a severe security vulnerability. The WPScan team, on 11/14/2023, brought this alarming issue to light, identifying the vulnerability as CVE-2023-6063 and assigning it a high-severity score of 8.6. This vulnerability affects all plugin versions preceding the recently released 1.2.2 update.

Understanding SQL Injection Vulnerabilities

SQL injection vulnerabilities arise when software fails to properly validate user input, allowing malicious actors to manipulate SQL queries directly. In the case of WP Fastest Cache, the flaw lies in the 'is_user_admin' function of the 'WpFastestCacheCreateCache' class. This function, responsible for checking if a user is an administrator, extracts the '$username' value from cookies without proper sanitization.

Exploiting the Flaw

The unfiltered '$username' input becomes a potential entry point for attackers. By manipulating this cookie value, hackers can alter the SQL query executed by the plugin, gaining unauthorized access to the website's database. WordPress databases typically store sensitive information such as user data (IP addresses, emails, IDs), account passwords, plugin and theme configurations, and other critical data necessary for a site's functionality.

The Urgency for Action

With more than 600,000 websites still running vulnerable versions of WP Fastest Cache, immediate action is imperative.On November 27, 2023, WPScan intends to unveil a proof-of-concept (PoC) exploit targeting CVE-2023-6063.. However, it's crucial to note that the vulnerability isn't overly complex, and cybercriminals may exploit it before the official release of the PoC.

The Solution: Update to Version 1.2.2

Acknowledging the severity of the situation, WP Fastest Cache developers swiftly addressed the issue and released a fix in version 1.2.2, which became available as of [previous date]. All users of the plugin are strongly advised to upgrade to the latest version without delay, ensuring their websites are shielded from potential security breaches.

In conclusion, the revelation of this SQL injection vulnerability in WP Fastest Cache underscores the constant need for vigilance in the digital landscape. Website owners and administrators must prioritize security measures, keeping their plugins and systems up-to-date to thwart potential cyber threats and safeguard sensitive information.

Proof of Concept


Contributed by Sandeep Vishwakarma

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