CVE-2025-30687

What it actually does

The flaw in the MySQL Server Optimizer component permits a low-privileged network attacker to trigger a hang or repeatable crash resulting in complete denial of service.

Why it matters to the business

Database services become unavailable, interrupting dependent applications and causing operational downtime until the server is restarted or the issue is resolved.

How an attack unfolds

An attacker with valid low-privileged credentials connects to the MySQL server over the network and submits specially crafted queries that exercise the optimizer, causing the server process to hang or crash.

How to fix it

Upgrade MySQL Server to a fixed version beyond 8.0.41, 8.4.4, or 9.2.0 as appropriate for the release stream, apply vendor patches promptly, and restrict unnecessary network access.

How to confirm the fix worked

Verify the installed MySQL version is outside the affected ranges, review release notes for the applied fix, and confirm the server remains stable under equivalent query workloads.

Typical attack path

1. Obtain low-privileged network access to the MySQL server
2. Establish a connection using supported protocols
3. Issue crafted queries targeting the optimizer component
4. Induce repeated crashes or hangs to sustain denial of service

How to detect it

Review MySQL error logs and system crash dumps for optimizer-related failures or abrupt terminations, correlate with authentication events from low-privileged accounts, and watch for spikes in server restarts.

What your security team should do

• Prioritize patching all affected MySQL instances to eliminate the denial-of-service condition
• Limit network exposure of database servers and enforce least-privilege accounts
• Monitor for unusual query patterns or repeated server restarts in logs
• Test upgrades in staging environments before production deployment