Published: June 2024
Severity: CVSS 4.9 (Availability)
Affected Versions: MySQL 8.4.-8.4.4, 9..-9.2.
Component: Server: DML (Data Manipulation Language)
Vector: Network, High Privilege, No User Interaction
CVE Reference: NVD - CVE-2025-21588
Oracle Advisory: Oracle Critical Patch Update Advisory - July 2024

Overview

CVE-2025-21588 is a newly disclosed vulnerability impacting specific supported versions of the MySQL Server product, particularly focusing on the DML component. The issue is classified as a Denial of Service (DoS) vulnerability, letting attackers with high-level privileges — like those granted to DBAs or system administrators — to send crafted network requests that can hang or crash the MySQL server. This crash may result in repeated downtime, disrupting applications and workflows dependent on MySQL.

While this flaw doesn’t allow access to confidential data or the ability to modify data, its ease of exploitation and severe availability impact make it important to review for anyone managing affected MySQL installations.

Technical Details

The vulnerability arises in DML operations (like INSERT, UPDATE, DELETE, SELECT), which are the core query methods in MySQL. An attacker, having already obtained high-privileged access (such as the SUPER or DBA role), can send a specifically crafted DML statement — possibly over multiple network protocols (TCP, UNIX socket, etc.) — that triggers a logic flaw or unhandled exception inside the database engine. This results in a server hang or crash, requiring manual intervention to recover.

Key Points

- Attack Surface: SQL protocol over TCP/IP, socket, or similar, authenticated local or remote users.
- Exploit Complexity: Low. Exploiting the vulnerability is straightforward after privileges are attained.
- Impact: Complete denial of service — normal operation of MySQL server is halted or made unstable. No information disclosure or alteration, but sustained outages may result.

Proof-of-Concept Example

An exploit for this bug generally involves running a specially crafted DML SQL statement against the vulnerable MySQL instance. An example (representative, not the exact payload):

-- Assume attacker has SUPER privileges
-- The following is a dummy pattern for demonstration purposes
SET SESSION sql_mode=''; -- remove strict checks
CREATE TABLE dos_test (id INT PRIMARY KEY, data TEXT);

-- This sequence of inserts with a specific crafted pattern triggers the bug
INSERT INTO dos_test (id, data) VALUES
  (1, REPEAT('A', 10000000)),
  (2, REPEAT('B', 10000000)),
  (3, REPEAT('C', 10000000));

-- The payload might leverage an edge case, causing a logic failure
INSERT INTO dos_test (id, data)
  SELECT id + 1, data FROM dos_test LIMIT 10000000;

*Note: Exact exploit details might differ; this is a simulated example to illustrate the scenario based on public advisory hints.*

When run, the database may hit an internal check failure, get stuck in resource exhaustion, and eventually crash with an out-of-memory, segmentation fault, or assertion error. Such a hang makes MySQL unreachable, resulting in a complete denial of service (DoS) until manual intervention.

Sends crafted DML SQL statement(s) that leverage an edge case or bug in DML handling.

3. The server encounters a crash/hang condition.

Repeated attempts result in consecutive outages (i.e., reproducible DoS).

Who is vulnerable:
Databases running MySQL 8.4.-8.4.4 or 9..-9.2. without recent security patches.

Mitigation & Recommendations

- Upgrade Immediately: Patch MySQL to the latest version outside the affected range (see official downloads).
- Restrict Privileges: Only grant high-level privileges (SUPER, DBA, etc.) to absolutely necessary users.
- Network Filtering: Where possible, restrict network access to trusted segments/subnets and use firewalls to limit attack surfaces.
- Monitor Logs: Watch for abnormal DML activity or unexplained server restarts and investigate immediately.

References & Further Reading

- CVE-2025-21588 - National Vulnerability Database
- Oracle Critical Patch Update Advisory - July 2024
- MySQL Security Updates
- HackerOne / Bugcrowd (Search for DoS in MySQL) *(for similar disclosed cases)*

Conclusion

CVE-2025-21588 shows that even high-privileged, internal-only vulnerabilities in core components like MySQL’s DML processing can have dramatic operational impacts. If your environment runs any affected MySQL version, patching is your strongest defense. Always follow least-privilege principles, monitor server health, and apply updates as released. Prevention is crucial: a single well-placed attack—especially from an internal threat—can lock down critical database infrastructure.

Timeline

Published on: 04/15/2025 21:15:54 UTC
Last modified on: 04/19/2025 01:15:44 UTC