CVE-2024-21239

What it actually does

Allows high privileged network attacker to trigger a hang or repeatable crash in the InnoDB component of MySQL Server resulting in complete denial of service.

Why it matters to the business

Causes database downtime that interrupts dependent applications and business processes; low EPSS and no KEV status reduce immediate ransomware urgency but still requires patching of widely used versions.

How an attack unfolds

Attacker with high privileges connects over supported protocols and sends crafted requests that exploit the InnoDB flaw, forcing the server into a hung or crashed state.

How to fix it

Upgrade MySQL Server past 8.0.39, 8.4.2 and 9.0.1; for org.apache.kafka:connect (Maven) upgrade to 3.4.0.

How to confirm the fix worked

Confirm MySQL version is newer than the listed affected releases and test that the server remains stable under high-privileged load after upgrade.

Typical attack path

1. Obtain high-privileged network credentials to MySQL Server
2. Connect via multiple protocols to the target instance
3. Transmit malicious InnoDB-targeted requests
4. Induce hang or crash to achieve denial of service

How to detect it

Review database error and crash logs for repeated InnoDB failures immediately following high-privileged connections; correlate with authentication events from privileged accounts.

What your security team should do

• Apply the listed fixed versions immediately
• Audit and minimize high-privileged database accounts
• Monitor for unusual crash or hang events in database logs