CVE-2026-102466: Maven/io.vertx/vertx-mysql-client vulnerability
In Eclipse Vert.x versions [4.0.0, 4.5.34] or [5.0.0,5.0.12] or [5.1.0,5.1.9] or [5.2.0, 5.2.0], the Vert.x MySQL client (vertx-mysql-client) pre-allocates an array for column definitions based on a server-declared column count with no upper-bound validation. A malicious or compromised MySQL server, or an attacker with man-in-the-middle positioning, can send a crafted result set packet with an extremely large column count, causing the client to attempt a massive heap allocation. The resulting OutOfMemoryError crashes the Netty event loop thread, causing a complete denial of service for all connections and verticles in the Vert.x application.
The impacted component is io.vertx:vertx-mysql-client.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed to this issue?
Applications using io.vertx:vertx-mysql-client in the affected 4.x or 5.x version ranges are exposed when they connect to a malicious or compromised MySQL server, or when an attacker can manipulate the MySQL connection as a man in the middle.
What does an attacker need to do to trigger the denial of service?
The attacker must cause the client to receive a crafted MySQL result-set packet declaring an extremely large column count. The client then attempts to pre-allocate an array of that size without an upper-bound check.
What is the operational impact if exploitation succeeds?
The oversized allocation can produce an OutOfMemoryError that crashes the Netty event loop thread. This causes a complete denial of service for all connections and verticles in the Vert.x application.