GHSA-68mj-5wr7-6fgg RabbitMQ Java client ValueReader: Oversized LongString/bytes length triggers OOM via unchecked allocation

• Maven com.rabbitmq:amqp-client: < 5.33.1 → fixed in 5.33.1

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.