RabbitMQ Java client: Unvalidated Class.forName in JSON-RPC ProcedureDescription enables arbitrary class loading

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-63337
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-18 17:17:00 UTC
Updated2026-08-18 20:17:20 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v4.0 7.5 HIGH from [email protected]

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-470 | CWE-470 CWE-470: Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary7.5HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/E:X/C...
4.0CNADECLARED7.5HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
Low
User Interaction
Passive
Confidentiality
High
Integrity
High
Availability
High
Sub Conf.
Low
Sub Integrity
Low
Sub Availability
Low

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Rabbitmq Rabbitmq-java-client affected < 5.33.0 Not specified

References

ReferenceSourceLinkTags
github.com/rabbitmq/rabbitmq-java-client/pull/2000 [email protected] github.com
github.com/rabbitmq/rabbitmq-java-client/commit/9f8e7efd0c648f235dc0e962... [email protected] github.com
github.com/rabbitmq/rabbitmq-java-client/commit/0032f75f9dc3df847f94b2b8... [email protected] github.com
github.com/rabbitmq/rabbitmq-java-client/releases/tag/v5.33.0 [email protected] github.com
github.com/rabbitmq/rabbitmq-java-client/pull/2002 [email protected] github.com
github.com/rabbitmq/rabbitmq-java-client/security/advisories/GHSA-6g32-p... 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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