The RabbitMQ Java client library allows Java and JVM-based applications to connect to and interact with RabbitMQ nodes. Prior to 5.33.1, src/main/java/com/rabbitmq/client/impl/ValueReader.java uses ValueReader.readBytes to accept a wire-declared contentLength below Integer.MAX_VALUE and allocate a byte array before checking the bytes available in the frame. A malicious AMQP peer can send a LongString or byte-array field with type tag S and a declared length such as 0x7FFFFFFE during the pre-authentication connection.start server-properties table, causing an approximately 2 GB allocation and OutOfMemoryError before readFully consumes data. The resulting memory exhaustion can terminate the JVM and cause denial of service. This issue is fixed in version 5.33.1.

Affected: Maven: com.rabbitmq:amqp-client

## Summary

`ValueReader.readBytes()` allocates a byte array sized by a wire-declared content length without validating it against actual frame data. A malicious AMQP peer triggers OOM by declaring a ~2GB string/bytes field.

## Vulnerable Code

`src/main/java/com/rabbitmq/client/impl/ValueReader.java` lines 83-95:

```java private static byte[] readBytes(final DataInputStream in) throws IOException { final long contentLength = unsignedExtend(in.readInt()); if(contentLength < Integer.MAX_VALUE) { final byte[] buffer = new byte[(int)contentLength]; // allocates before reading in.readFully(buffer); return buffer; } } ```

## Attack Scenario

A malicious AMQP server sends a LongString field (type tag 'S') with declared length `0x7FFFFFFE` (2,147,483,646). The check `contentLength < Integer.MAX_VALUE` passes. `new byte[2147483646]` attempts ~2GB allocation, causing `OutOfMemoryError` before `readFully()` attempts to read data.

The allocation size is attacker-controlled and is NOT validated against the frame size or `TruncatedInputStream` bounds. Exploitable pre-authentication via `connection.start` server-properties table.

## Impact

Denial of service via JVM `OutOfMemoryError`. Crashes the entire JVM.

## CWE

CWE-789: Memory Allocation with Excessive Size Value

## Remediation

Validate `contentLength` against the frame's remaining bytes or the negotiated max frame size (default 131,072) before allocating.

Affected: openEuler:24.03-LTS-SP3: rabbitmq-java-client, openEuler:24.03-LTS-SP4: rabbitmq-java-client, openEuler:20.03-LTS-SP4: rabbitmq-java-client, openEuler:22.03-LTS-SP4: rabbitmq-java-client, openEuler:24.03-LTS-SP1: rabbitmq-java-client

The library allows Java code to interface to AMQP servers. Please see the specification page for more information on AMQP inter-operation and standards-conformance You will need an AMQP server, such as our very own RabbitMQ server, to use with the client library. Security Fix(es):

The RabbitMQ Java client library allows Java and JVM-based applications to connect to and interact with RabbitMQ nodes. `maxBodyLebgth` was not used when receiving Message objects. Attackers could send a very large Message causing a memory overflow and triggering an OOM Error. Users of RabbitMQ may suffer from DoS attacks from RabbitMQ Java client which will ultimately exhaust the memory of the consumer. This vulnerability was patched in version 5.18.0.(CVE-2023-46120)

The RabbitMQ Java client library allows Java and JVM-based applications to connect to and interact with RabbitMQ nodes. Prior to 5.33.0, the AMQP connection tuning path records the negotiated AMQP frame_max value, but src/main/java/com/rabbitmq/client/impl/SocketFrameHandler.java and NettyFrameHandlerFactory continue to validate broker-controlled frame payload lengths against maxInboundMessageBodySize because the negotiated limit is not applied consistently through setMaxInboundFramePayloadSize. A malicious or compromised broker can send a method frame larger than the negotiated frame_max during or after connection establishment, causing the client to allocate and decode a protocol-invalid frame instead of rejecting it with Ma…

Affected: Ubuntu:18.04:LTS: rabbitmq-java-client, Ubuntu:20.04:LTS: rabbitmq-java-client, Ubuntu:22.04:LTS: rabbitmq-java-client, Ubuntu:24.04:LTS: rabbitmq-java-client, Ubuntu:26.04:LTS: rabbitmq-java-client

The RabbitMQ Java client library allows Java and JVM-based applications to connect to and interact with RabbitMQ nodes. Prior to 5.33.1, src/main/java/com/rabbitmq/client/impl/ValueReader.java uses ValueReader.readBytes to accept a wire-declared contentLength below Integer.MAX_VALUE and allocate a byte array before checking the bytes available in the frame. A malicious AMQP peer can send a LongString or byte-array field with type tag S and a declared length such as 0x7FFFFFFE during the pre-authentication connection.start server-properties table, causing an approximately 2 GB allocation and OutOfMemoryError before readFully consumes data. The resulting memory exhaustion can terminate the JVM and cause denial of service. This issue is fixed in version 5.33.1.