CVE-2026-63335 RabbitMQ Java client malformed body frame triggers raw command assembler exception
A malicious broker can cause a denial of service in RabbitMQ Java client applications by sending malformed AMQP frames that trigger an unhandled exception.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-63335?
CVE-2026-63335 is a medium-severity denial of service vulnerability in rabbitmq-java-client, published on 18 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The RabbitMQ Java client library allows Java and JVM-based applications to connect to and interact with RabbitMQ nodes. Prior to 5.31.0, inbound AMQP command assembly in src/main/java/com/rabbitmq/client/impl/CommandAssembler.java processes a content-bearing method and header whose remainingBodyBytes value is smaller than a following AMQP.FRAME_BODY payload. CommandAssembler.consumeBodyFrame subtracts the peer-controlled payload length before validating that it fits, drives remainingBodyBytes negative, and throws a raw UnsupportedOperationException instead of MalformedFrameException. A malicious or compromised broker peer can send this malformed sequence on an open nonzero channel to terminate frame processing and close the client connection, causing denial of service for work using that connection. This issue is fixed in version 5.31.0.
Weakness: CWE-20
Which versions are affected by CVE-2026-63335?
2 open source packages ship an affected version, including com.rabbitmq:amqp-client.
| Package | Affected | Fixed in |
|---|---|---|
com.rabbitmq:amqp-client Maven | All versions | 5.31.0 |
com.rabbitmq:amqp-client Maven | All versions | 5.31.0 |
How do I fix CVE-2026-63335?
Upgrade com.rabbitmq:amqp-client to 5.31.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-63335 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-63335 exists.
Sources
Also known as CLEANSTART-2026-ZR37336, DEBIAN-CVE-2026-63335, ECHO-3ae4-9a50-4ad6, GHSA-qx7j-jv8m-fppr, MINI-2949-7x2v-jc37, MINI-38qp-m9pg-crc9 and 14 more.