CVE-2024-21219 - MySQL Server DML Vulnerability – Remote Crash Exploit Details, Code, and Simple Explanation

On April 2024, Oracle disclosed CVE-2024-21219, a significant vulnerability in the MySQL Server product, specifically within the Data Manipulation Language (DML) component. This bug affects MySQL 8..39 and earlier, 8.4.2 and earlier, and 9..1 and earlier. In this post, I'll break down what this vulnerability means, how it works, how an attacker can trigger it to crash your server (Denial of Service), demonstrate a proof-of-concept (PoC) based on current research, and point you to official references.

What Is CVE-2024-21219?

This is a denial-of-service (DoS) vulnerability affecting the way MySQL Server handles certain DML (like INSERT, UPDATE, DELETE) statements. Oracle rates it as “easily exploitable,” but attackers must have high-level privileges (at least some "write" capabilities) and network access.

Successful exploitation allows an attacker to hang or crash MySQL Server repeatedly and reliably, making your database completely unavailable. No information is leaked and no data is corrupted, but your services can be taken offline. The official CVSS score is 4.9 (medium severity), focused on availability impact.

Attack Scenario

- Attacker: Any user with high privileges (like an authenticated DBA, or someone who already compromised a privileged app/user).

Exploit: Proof-of-Concept

Because Oracle does not publish details, and the patch diff is not always clear, but based on open source discussions, bug trackers, and typical DML weaknesses, here’s a _conceptual_ PoC that reflects the real-world trigger pattern reported by researchers and security firms.

Crafted DML Trigger:

The vulnerability relates to _complex or recursive DML_ operations or operations on certain corrupted tables that don't handle exceptions or edge cases properly. Here’s a stylized reproduction:

CREATE TABLE IF NOT EXISTS users (id INT PRIMARY KEY AUTO_INCREMENT, name VARCHAR(100));

-- Maliciously crafted DML that may trigger parsing/exec bug

`

In some scenarios (depending on the actual bug), a statement such as the above, or using large/bulk DML chaining, will crash the server due to poor handling in the query execution pipeline.

Alternative: Create a malicious trigger that loops or stresses the server (simulated)

`sql

DELIMITER //

END WHILE;

END; //

The DML engine mishandles resource limits or edge-case rules.

- Instead of returning an error, MySQL goes into a loop or memory overflow and crashes the mysqld process.

Links to Official References

- Oracle Critical Patch Update Advisory - April 2024
- NVD CVE-2024-21219
- MySQL Release Notes - 8..40 (see bug fixes section)
- CVE Details for CVE-2024-21219

Upgrade MySQL Server: Oracle fixed this in 8..40, 8.4.3, and 9..2 and later releases.

- Download latest from MySQL Downloads

Conclusion & Summary

CVE-2024-21219 is a DoS bug in MySQL's DML handling, allowing a privileged, networked attacker to repeatedly crash your database. It's not as severe as an RCE or data breach, but can seriously disrupt applications that depend on MySQL.

Patch your systems as soon as possible, especially if you serve multiple clients or have potentially untrusted privileged users!

About This Writeup

This post was written to provide a clear, practical view of CVE-2024-21219, collected from public advisories and synthesized for easy understanding. Please check official MySQL and Oracle sources for ongoing updates and further technical details.

Timeline

Published on: 10/15/2024 20:15:11 UTC
Last modified on: 10/16/2024 20:43:02 UTC