Vulnerability · Published Aug 18, 2026 · Assigned by GitHub_M
CVE-2026-63337RabbitMQ Java client: Unvalidated Class.forName in JSON-RPC ProcedureDescription enables arbitrary class loading
High 7.5
In plain English
A high-severity security flaw in rabbitmq-java-client from rabbitmq. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
The RabbitMQ Java client library allows Java and JVM-based applications to connect to and interact with RabbitMQ nodes. Prior to 5.33.0, com.rabbitmq.tools.jsonrpc.ProcedureDescription receives a javaReturnType value in an untrusted system.describe response and passes it through JSONUtil.tryFill, setJavaReturnType, and computeReturnTypeAsJavaClass to Class.forName(javaReturnType) with initialization enabled. An attacker able to answer the JsonRpcClient request through a shared broker or network interception can select a class already present in the victim JVM and trigger its static initializer, while JsonRpcClient.java later passes getReturnType output to mapper.parse and may also create type confusion. Successful exploitation can affect confidentiality, integrity, and availability in the client process. This issue is fixed in version 5.33.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | rabbitmq-java-client | no fix listed | DEBIAN-CVE-2026-63337 |
| Debian:13 | rabbitmq-java-client | no fix listed | DEBIAN-CVE-2026-63337 |
| Maven | com.rabbitmq:amqp-client | 5.33.0 | GHSA-6g32-pxv4-2wfj |
| Ubuntu:22.04:LTS | rabbitmq-java-client | no fix listed | UBUNTU-CVE-2026-63337 |
| Ubuntu:24.04:LTS | rabbitmq-java-client | no fix listed | UBUNTU-CVE-2026-63337 |
| Ubuntu:26.04:LTS | rabbitmq-java-client | no fix listed | UBUNTU-CVE-2026-63337 |
| Ubuntu:26.10 | rabbitmq-java-client | no fix listed | UBUNTU-CVE-2026-63337 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| rabbitmq | rabbitmq-java-client | < 5.33.0 |
Weakness: CWE-470 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L
References
- https://github.com/rabbitmq/rabbitmq-java-client/security/advisories/GHSA-6g32-pxv4-2wfj x_refsource_CONFIRM
- https://github.com/rabbitmq/rabbitmq-java-client/pull/2000 x_refsource_MISC
- https://github.com/rabbitmq/rabbitmq-java-client/pull/2002 x_refsource_MISC
- https://github.com/rabbitmq/rabbitmq-java-client/commit/0032f75f9dc3df847f94b2b85a16119250bf63cb x_refsource_MISC
- https://github.com/rabbitmq/rabbitmq-java-client/commit/9f8e7efd0c648f235dc0e96232ae7efa75ea4fa8 x_refsource_MISC
- https://github.com/rabbitmq/rabbitmq-java-client/releases/tag/v5.33.0 x_refsource_MISC