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CVE-2026-63337

Updated on 18 Aug 2026

Severity

7.5 High severity

Details

CVSS score
7.5
CVSS 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/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
CWE ID
Links
NISTCIRCLRHELUbuntu

Overview

About vulnerability

The JSON-RPC tools in com.rabbitmq.tools.jsonrpc perform Class.forName(javaReturnType) with initialize=true on class names received from untrusted AMQP messages, without any validation or allowlist.

Vulnerable code (ProcedureDescription.java:101-127): When a JsonRpcClient connects, it calls system.describe and receives a service description from the AMQP queue. The response JSON includes javaReturnType fields that are reflectively set via JSONUtil.tryFill(), triggering setJavaReturnType() → computeReturnTypeAsJavaClass() → Class.forName(javaReturnType).

Attack scenario:

  1. Victim uses JsonRpcClient to connect to a JSON-RPC service via RabbitMQ
  2. Attacker (co-tenant on shared broker, or MITM) intercepts the system.describe request
  3. Attacker responds with crafted javaReturnType values
  4. Victim’s client calls Class.forName(attackerInput) with default initialize=true
  5. Static initializers of attacker-specified classes execute in victim’s JVM

Additionally, the loaded class from getReturnType() is passed to mapper.parse(replyStr, expectedType) at JsonRpcClient.java:168, potentially enabling type-confusion.

Recommended fix: Use Class.forName(javaReturnType, false, classLoader) to prevent static initializer execution, or add an allowlist of permitted return types.

CWE: CWE-470

Reply from reporter (2026-06-29): Thanks for the quick turnaround. Fix looks good. Looking forward to the CVE assignment.

Details

Affected product:
Spring , alluxio , camel , metrics , micrometer , pulsar , rabbitmq-java-client
Affected packages:
Spring Integration @ 5.5.19 (+3277 more)

Fixes