Oracle MySQL has identified a vulnerability in its MySQL Server product that could potentially lead to a Denial of Service (DOS) attack. This specific vulnerability is denoted by the code CVE-2023-21917 and targets the Optimizer component of the MySQL Server package. MySQL Server versions affected are 8..30 and prior. In this post, we will discuss the details of the exploit, possible code implementations, and provide links to original references to help better understand and mitigate this issue.

Vulnerability Details

An attacker with high privilege and network access via multiple protocols can exploit this vulnerability resulting in unauthorized ability to cause a hang or frequently repeatable crash of the MySQL Server. The CVSS 3.1 Base Score of this vulnerability is 4.9 out of 10, which is categorized as a medium-severity issue with the major impact on system availability. The CVSS Vector is (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).

Exploit Details

Since the vulnerability lies in the MySQL Server's Optimizer component, the attacker would likely exploit it by manipulating SQL query optimization operations to cause the server to crash or hang. Due to the technical nature of this vulnerability, specific code snippets showcasing the exploit cannot be shared in this post for security reasons. However, one could imagine an attacker using a specially crafted SQL query or series of queries that overload or confuse the optimizer, leading to unintended Server behavior.


The reference documentation for CVE-2023-21917 can be found on the official Oracle website (link1), alongside the details of the vulnerability and other affected products. Additionally, the MySQL Server documentation (link2) provides further information on its components and features, including the Optimizer component, which can be useful for understanding the affected technology and devising possible mitigation strategies.

1. Oracle Critical Patch Update Advisory:
2. MySQL Server Documentation:


CVE-2023-21917 is a medium-severity vulnerability that affects the MySQL Server component Optimizer, potentially leading to unauthorized DOS attacks on the server by high privileged attackers. Users running affected versions (8..30 and prior) should take immediate action to mitigate the risk, update their systems and review the related reference resources mentioned above. By staying informed and taking preventive measures, it is possible to avoid potential data loss or system compromisation caused by this vulnerability.


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