In today's world, where data is an integral part of any organization, the safety and security of databases are of utmost importance. Recently, a vulnerability has been discovered in the MySQL Server product of Oracle MySQL (component: Server: DDL). This post aims to provide readers with detailed information about this vulnerability, its effects, potential risks, and how to address it.

Vulnerability Details

The vulnerability has been designated as CVE-2023-21933, affecting MySQL Server version 8..32 and prior. It is classified as "easily exploitable," allowing high privileged attackers with network access via multiple protocols to compromise the MySQL Server. The successful exploitation of this vulnerability could result in unexpected system behavior, such as a hang or frequently repeatable crash (complete Denial of Service or DOS) of the MySQL Server. The CVSS 3.1 Base Score for this vulnerability is 4.9, with availability impacts being the primary concern. The CVSS Vector is represented as (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).

Exploit Details

The vulnerability is found within the Server: DDL component of MySQL Server, specifically when handling requests for data definition operations, such as creating or altering tables. The following code snippet demonstrates a possible exploit:

# Attacker-controlled input
malicious_query = "ALTER TABLE example_table ENGINE=InnoDB ROW_FORMAT=COMPRESSED;"

# Send the query to the vulnerable MySQL Server application

In this example, the attacker sends a specially crafted query that forces the Server: DDL component to process and execute the request. As a result, the application could crash or hang, disrupting the normal operations of the MySQL Server.

Mitigations and Protecting Your System

To effectively protect your MySQL Server from this vulnerability, consider taking the following steps:

1. Update your MySQL Server to the latest version, which includes patches to address this vulnerability. For version 8..32 and prior, update to version 8..33 or later. To learn more about updating MySQL Server, visit the official documentation:

2. Restrict access to your MySQL Server by implementing firewalls or network access controls, allowing only trusted and authorized users to have access to sensitive functions.

3. Regularly monitor your MySQL Server for suspicious activities, such as repeated crashes or hangs. Investigate any possible signs of exploitation.

4. Apply the principle of least privilege to user accounts, ensuring that they only have access to the minimum required permissions to perform their job functions.


The discovery and understanding of vulnerabilities like CVE-2023-21933 are essential steps towards ensuring a secure and reliable computing environment. It is crucial for system administrators and developers to follow best practices, invest in regular updates, restrict access, and monitor systems closely to minimize risks associated with vulnerabilities such as this one.

Remember, a secure system is a reliable system, so stay alert and always be proactive in protecting and enhancing the overall security of your web applications and infrastructure.


Published on: 04/18/2023 20:15:00 UTC
Last modified on: 04/27/2023 15:15:00 UTC