CVE-2017-3302

What it actually does

Use-after-free in libmysqlclient.so triggered during network packet processing leads to denial-of-service crash with no confidentiality or integrity impact.

Why it matters to the business

Database-dependent applications may experience sudden crashes and downtime when connecting to untrusted or compromised servers; the issue affects very old releases with stable low exploitation probability and no ransomware usage.

How an attack unfolds

An attacker hosts a malicious MySQL server or performs a man-in-the-middle attack; when a vulnerable client connects, the server returns crafted responses that trigger the use-after-free in the client library, causing an immediate crash.

How to fix it

Upgrade mysql/mysql-server to the version containing commit 2793382d656158e3b72451dc47a4ea022b566f7d; ensure deployments run MySQL 5.6.21 or newer, 5.7.5 or newer, or the corresponding fixed MariaDB releases.

How to confirm the fix worked

Confirm installed version is newer than the vulnerable ranges listed in the advisory and perform connection tests against both benign and malformed servers to verify absence of crashes.

Typical attack path

1. Position malicious MySQL server or intercept client traffic
2. Wait for vulnerable client to initiate connection
3. Send specially crafted authentication or result packets
4. Trigger use-after-free in libmysqlclient resulting in crash

How to detect it

Search application and system logs for abrupt crashes mentioning libmysqlclient around connection establishment; review network traffic for unexpected MySQL protocol responses from external hosts.

What your security team should do

• Apply the fixed commit or upgrade all affected MySQL and MariaDB instances immediately
• Restrict database clients to connect only to trusted servers
• Monitor application and system logs for unexpected client-library crashes