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CVE-2026-63337
Published:August 18, 2026
Updated:September 23, 2026
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
https://github.com/rabbitmq/rabbitmq-java-client.git (GITHUB):
Affected version(s) >=v4.0.0.M1 <v5.33.0
Fix Suggestion:
Update to version v5.33.0
com.rabbitmq:amqp-client (JAVA):
Affected version(s) >=1.3.0 <5.33.0
Fix Suggestion:
Update to version 5.33.0
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CVSS v4
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
LOW
User Interaction
PASSIVE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
HIGH
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
LOW
Subsequent System Integrity
LOW
Subsequent System Availability
LOW
CVSS v3
Base Score:
9
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Weakness Type (CWE)
Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
EPSS
Base Score:
0.32