Medium · published October 15, 2026
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 Redis client RESP parser pre-allocates arrays to a length declared by the server without enforcing an upper bound. A malicious or compromised Redis server, or an attacker in a man-in-the-middle position, can send a crafted RESP response declaring an extremely large array, push, or attribute length, causing the client to attempt a massive heap allocation. The resulting OutOfMemoryError crashes the Vert.x event loop thread, denying service to all connections and verticles sharing that loop.
The impacted component is io.vertx:vertx-mysql-client.
| Product | Versions | Fixed in |
|---|---|---|
| eclipse/vert.x | ≥ 4.5.0, < 4.5.35 | 4.5.35 |
| eclipse/vert.x | ≥ 5.0.0, < 5.1.10 | 5.1.10 |
| eclipse/vert.x | all versions | — |