CVE-2026-63337

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

HIGH
7.5
CVSS Score
Published: August 18, 2026 at 04:27 PM UTC
Updated: October 22, 2026 at 10:10 PM UTC
1 product affected across 1 vendorRabbitmq Java Client

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Severity
HIGH7.5
Exploit prediction
EPSS 0.6%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 5.33.0
Affected range stops below 5.33.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-470

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