Security Vulnerabilities
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 Eclipse Vert.x MQTT (vertx-mqtt) MqttClient stores every inbound QoS 2 PUBLISH message received from the broker in an internal map (qos2inbound) while awaiting the corresponding PUBREL packet to complete the QoS 2 handshake. This map has no size limit; the maxInflightQueue option is enforced only on the outbound publish path and does not constrain inbound message retention.
A malicious or compromised MQTT broker can exploit this by sending QoS 2 PUBLISH messages with distinct packet identifiers and withholding the PUBREL responses. Each incomplete handshake causes the client to retain the full publish message (topic, payload, and metadata) indefinitely, leading to unbounded memory growth in the Vert.x process. This can degrade the MQTT-consuming application or cause out-of-memory termination.
The impacted component is io.vertx:vertx-mqtt.
CVSS Score
8.2
EPSS Score
0.003
Published
2026-10-15
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.
CVSS Score
8.2
EPSS Score
0.003
Published
2026-10-15
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 DB2 client (vertx-db2-client) contains DRDA protocol handling code that deserializes User Defined Type (UDT) column data using a bare ObjectInputStream.readObject() call with no ObjectInputFilter or class allowlist.
This code path is triggered when a DRDA server sends a result set with a column tagged as UDT (FDOCA protocol LID 0x50). However, DB2 does not support this type of UDT. The FDOCA 0x50 type is never sent by a legitimate DB2 server.
Nevertheless, a malicious or man-in-the-middle DRDA server could craft a response with a 0x50-tagged column, causing the client to deserialize arbitrary attacker-controlled bytes on the Vert.x event loop before any application code can inspect or reject the data. If a Java deserialization gadget chain is present on the application's classpath, this enables remote code execution. Without a gadget chain, denial of service is possible via crafted object graphs. TLS is disabled by default, making man-in-the-middle exploitation feasible.
The impacted component is io.vertx:vertx-db2-client.
CVSS Score
9.2
EPSS Score
0.004
Published
2026-10-15
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], a gRPC endpoint does have a configurable per message maximum size in bytes, however the maximum size applies to the received bytes. When applied to a compressed message, this only applies to the compressed size and not the actual size of the uncompressed content. This can be used to force a gRPC endpoint to allocate more bytes than the value defined by the configuration, making the endpoint vulnerable to compression bomb attacks.
The impacted component is io.vertx:vertx-gprc-server.
CVSS Score
8.7
EPSS Score
0.003
Published
2026-10-15
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 PostgreSQL message decoder reads the 4-byte message length field from the PostgreSQL wire protocol without any maximum validation. A malicious, compromised, or man-in-the-middle PostgreSQL server can send a message header with the length field set to an extremely large value (up to Integer.MAX_VALUE), causing the decoder to accumulate subsequent TCP data into a composite buffer without bound, leading to unbounded memory allocation on the client and an out-of-memory crash. This occurs before authentication completes.
The impacted component is io.vertx:vertx-pg-client.
CVSS Score
8.2
EPSS Score
0.003
Published
2026-10-15
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 MySQL message decoder aggregates inbound multi-packet payloads into a composite direct-memory buffer without any cumulative size limit. A malicious, compromised, or man-in-the-middle MySQL server can send a continuous stream of packets with the maximum payload length (0xFFFFFF), preventing the end-of-message condition from being reached, causing unbounded direct-memory allocation on the client and leading to an out-of-memory crash. This occurs before authentication completes.
The impacted component is io.vertx:vertx-mysql-client.
CVSS Score
8.2
EPSS Score
0.003
Published
2026-10-15
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 uniqueItems keyword validation uses an O(n²) pairwise comparison loop with no short-circuit or size limit. A remote unauthenticated attacker can submit a moderately-sized JSON array that consumes disproportionate CPU time, leading to denial of service.
The impacted component is io.vertx:vertx-json-schema.
The following Vert.x modules depend on vertx-json-schema and are also affected:
io.vertx:vertx-web-openapi-router io.vertx:vertx-web-validation io.vertx:vertx-openapi
CVSS Score
8.7
EPSS Score
0.004
Published
2026-10-15
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.
CVSS Score
8.2
EPSS Score
0.002
Published
2026-10-15
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 WebSocket implementation does not define a maximum number of bytes allocation when decompressing frames or messages. This can be used to implement DDOS attacks with a zip bomb.
The impacted component is io.vertx:vertx-core.
CVSS Score
8.7
EPSS Score
0.003
Published
2026-10-15
In Eclipse Vert.x versions [5.0.0,5.0.12] or [5.1.0,5.1.9] or [5.2.0, 5.2.0], the HTTP proxy provides a body transformer interceptor that relies on a max buffered bytes limit to ensure a bounded buffer for each request. This can be used to force a server to indefinitely allocate heap. This vulnerability requires to use an intercepting body transformer.
The impacted component is io.vertx:vertx-http-proxy.
CVSS Score
8.7
EPSS Score
0.003
Published
2026-10-15