A new vulnerability, designated as CVE-2023-21966, has been identified in the MySQL Server product of Oracle MySQL, specifically within its Server: JSON component. Affected versions include 8..32 and earlier. This vulnerability allows a high privileged attacker with network access via multiple protocols to compromise MySQL Server. If successfully exploited, this vulnerability could grant unauthorized users the ability to hang or crash the MySQL Server repeatedly, resulting in a complete denial of service (DOS). The CVSS 3.1 Base Score for this vulnerability is 4.9, indicating significant availability impacts. The CVSS Vector is as follows: (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).

Here's a simple code snippet illustrating how the vulnerability might look like in a JSON object

  "data": {
    "payload": "MaliciousPayload"
  "type": "MySQL Server Vulnerability"

Original References

To learn more about this vulnerability (CVE-2023-21966) and to better understand its potential impact on your systems, it is highly recommended that you visit the original references provided by Oracle:

1. Oracle Critical Patch Update Advisory: https://www.oracle.com/security-alerts/cpujan2023.html
2. MySQL Server Release Notes: https://dev.mysql.com/doc/relnotes/mysql/8./en/news-8--32.html
3. CVE-2023-21966 in the National Vulnerability Database (NVD): https://nvd.nist.gov/vuln/detail/CVE-2023-21966

Exploit Details

An attacker that manages to exploit this vulnerability may successfully compromise the MySQL Server by causing a hang, crash, or complete denial of service attack. As a result, other users of the MySQL Server will be negatively affected; applications relying on MySQL Server will become unstable or unavailable, leading to severe disruptions in business operations and potential loss of data.

The attacker must, however, have high-level privileges to manipulate the server, as well as network access through multiple protocols, narrowing down the pool of potential perpetrators to those who have already gained access to the MySQL system through some other means. Thus, while the CVE-2023-21966 vulnerability may not directly result in data loss or unauthorized access to sensitive information, it can significantly disrupt a company's operations and result in financial or reputational losses.

Mitigation and Prevention

To prevent exploitation of this security vulnerability, it's crucial to apply the latest security patches from Oracle as soon as they become available. Oracle has provided an official security advisory detailing the necessary steps to update affected software versions: https://www.oracle.com/security-alerts/cpujan2023.html

In addition to keeping software up-to-date, users should also implement strict access controls on their MySQL servers, restricting high-level privileges to trusted personnel only. Employing robust network security measures, such as firewalls and network segmentation, can also help minimize the risk of unauthorized access to the MySQL server and protect sensitive data from potential attackers.


The CVE-2023-21966 vulnerability presents a major security risk to affected MySQL Server installations, with potentially severe impacts on the availability of the affected system. To minimize the risk of exploitation, users should regularly apply security patches provided by Oracle and implement strict access controls and network security measures. By taking these proactive steps to safeguard their systems, organizations can ensure the integrity and availability of their MySQL Server installations, thus helping to maintain efficient, secure operations in the long run.


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