# 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.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Aug 2026
- **Updated:** 18 Aug 2026
- **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, MINI-3m93-pv8p-7g3x, MINI-622h-r87v-m53r, MINI-69cf-x9xm-x638, MINI-72jj-4hpf-gpff, MINI-9g9f-87x9-xgm5, MINI-cr8h-j27w-98r4, MINI-crcx-ffgm-9hc6, MINI-h43x-2xjm-f263, MINI-j289-5mp7-4xqx, MINI-j86m-hvpx-hvw6, MINI-jmx5-722w-cgvv, MINI-m4r3-7788-6pqq, MINI-wg7h-6wxw-7ccj, UBUNTU-CVE-2026-63335

## 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 (Improper Input Validation)

## Which versions are affected by CVE-2026-63335?

2 open source packages ship an affected version, including com.rabbitmq:amqp-client.


| Package | Ecosystem | 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.

## Is CVE-2026-63335 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-63335 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63335 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-63335 exists.

Affected packages and fixed versions:
- com.rabbitmq:amqp-client (Maven): affected all versions; fixed in 5.31.0
- com.rabbitmq:amqp-client (Maven): affected all versions; fixed in 5.31.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-63335/ (Markdown: https://insights.sbomify.com/CVE-2026-63335/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63335
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63335
- OSV: https://osv.dev/vulnerability/CVE-2026-63335

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63335/
Summaries are generated and may contain mistakes; the official description above is the record.