In June 2024, Oracle revealed a new vulnerability—CVE-2024-21213—impacting MySQL Server's InnoDB component. It directly affects versions 8..39 and earlier, 8.4.2 and earlier, and 9..1 and earlier. This flaw lets a high-privileged local attacker, with a bit of help from a victim user, to crash or hang the MySQL Server, leading to complete denial of service (DoS).

In this write-up, we break down how this vulnerability works, share code snippets for understanding, and discuss its implications and how to stay safe.

What Is CVE-2024-21213?

CVE-2024-21213 targets the popular MySQL database’s InnoDB storage engine. According to Oracle’s official advisory:

User Interaction: Yes (needs a victim to interact, not just an attacker acting solo)

- Confidentiality/Integrity Impact: None (it won't leak or change data)

MySQL 9..1 and prior

CVSS Vector:
CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:U/C:N/I:N/A:H

This bug needs two things

1. A High-Privileged User: Someone with SUPER or admin-level rights _on the same machine running the server_.
2. Human Interaction: The attacker needs a legitimate user (like a DBA or app admin) to interact with the system (e.g., opening a database tool, running certain queries, etc.).

Technical Deep Dive

At its core, the vulnerability lives in InnoDB’s internal handling of certain operations. While Oracle hasn't published the full exploit scenario, it likely involves triggering a specific InnoDB operation that sends the server into a bad loop or crash, probably with malformed SQL or corrupt data pages.

When exploited, MySQL Server process will repeatedly crash or hang, causing a full denial of service.

Exploit Example

Below is a conceptual proof-of-concept. (Note: For safety, this is redacted to prevent actual misuse.)

Suppose the attacker and a target user both have access to the MySQL CLI or a management tool.

Step 1: Attacker preps the environment (e.g., by injecting a bad InnoDB table or a crafted SQL script).

Step 2: Attacker convinces the victim to execute a specific SQL command.

Step 3: The operation causes MySQL to crash or hang (DoS).

Example (pseudocode)

-- Attacker creates a malicious table that may exploit InnoDB's bug
CREATE TABLE poc_crash (
    id INT PRIMARY KEY,
    data VARCHAR(255)
) ENGINE=InnoDB;

-- Attacker inserts crafted data (could be malformed blobs, longstrings, etc.)
INSERT INTO poc_crash VALUES (1, REPEAT('A', 100000));

-- Attacker sends victim a SQL file or code to "test" (social engineering)
-- Victim runs this, perhaps as a routine or during maintenance:
ALTER TABLE poc_crash MODIFY COLUMN data TEXT;

-- This triggers the InnoDB flaw and MySQL process hangs/crashes

Please note: The real flaw may rely on more specific sequences or corruption of indexes, but the pattern holds—_attacker sets up, victim interacts, server dies_.

Original Oracle Advisory (July 2024):

Oracle Critical Patch Update Advisory - July 2024

NVD Entry for CVE-2024-21213:

https://nvd.nist.gov/vuln/detail/CVE-2024-21213

MySQL InnoDB Storage Engine Docs:

https://dev.mysql.com/doc/refman/8./en/innodb-introduction.html

Patch ASAP!

Update to the latest MySQL release as soon as Oracle ships a fix. See MySQL Download Page.

Train Staff:

Use security awareness to warn admins about social engineering (e.g., don’t run odd jobs from questionable sources).

Monitor & Alert:

Set up monitoring for repeated crashes/hangs—catch attacks quickly.

Conclusion

CVE-2024-21213 is a classic inside-job DoS risk, showing why privilege and user interaction controls matter on database servers. It’s not remote-code execution, nor does it leak data, but when a busy production DB goes down, that’s bad enough for any business.

Patch fast, train users, and keep your environment locked down.

Exclusive Write-up by [YourNameHere, 2024]

If you want more detailed technical breakdowns or quick help with patching, reach out to us, or bookmark this post for your DBA toolbox!

Timeline

Published on: 10/15/2024 20:15:10 UTC
Last modified on: 10/16/2024 20:43:51 UTC