CVE-2025-30685

What it actually does

The flaw in the Server: Replication component allows a high-privileged network attacker to trigger a hang or repeatable crash, resulting in complete denial of service to the MySQL Server process.

Why it matters to the business

Successful exploitation causes unplanned database outages that interrupt dependent applications, reporting, and transactions until the affected MySQL instance is restarted, increasing operational cost and risk of data inconsistency during failover.

How an attack unfolds

An attacker who already possesses high-privileged network credentials connects to a vulnerable MySQL instance and sends crafted replication protocol messages that trigger the flaw, causing the server to hang or crash repeatedly.

How to fix it

Apply the appropriate Oracle MySQL patch that resolves the replication issue for versions 8.0.0-8.0.41, 8.4.0-8.4.4 and 9.0.0-9.2.0; upgrade to the next released versions that contain the fix. Where the supplied fixed package data lists python2.7 updates, apply those operating-system level patches in parallel if the host also runs affected python2.7 packages.

How to confirm the fix worked

After patching, confirm the running MySQL version is newer than the affected ranges, re-test replication connectivity under load, and verify that the server remains stable when subjected to the previously crashing replication sequences.

Typical attack path

1. Obtain high-privileged network credentials for the target MySQL Server
2. Establish a connection over a supported protocol to the replication component
3. Transmit specially crafted replication traffic that exercises the vulnerable code path
4. Observe server hang or repeated crashes confirming denial of service

How to detect it

Inspect MySQL error logs and replication thread logs for repeated crash signatures or abrupt termination entries around the replication component; correlate with privileged login events from network sources.

What your security team should do

• Prioritize patching MySQL instances that allow network replication traffic from privileged accounts
• Review and reduce the number of accounts holding replication privileges
• Monitor EPSS trend and re-assess exploit maturity as new information appears
• Ensure database high-availability mechanisms are tested so that single-instance crashes do not cascade