RabbitMQ Java client: Unvalidated Class.forName in JSON-RPC ProcedureDescription enables arbitrary class loading
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- Passive
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| rabbitmq | rabbitmq-java-client | before 5.33.0 | 5.33.0 | Patch available | CNA |
| — | com.rabbitmq:amqp-client (Maven) | before 5.33.0 | 5.33.0 | Patch available | GHSA-6g32-pxv4-2wfj |
- rabbitmq-java-client Vendorrabbitmq Affected before 5.33.0 Fixed in 5.33.0 Patch available CNA
- com.rabbitmq:amqp-client (Maven) Vendor— Affected before 5.33.0 Fixed in 5.33.0 Patch available GHSA-6g32-pxv4-2wfj
Remediation
- Fix · CNA rabbitmq-java-client (rabbitmq) Fixed in 5.33.0
- Fix · GHSA-6g32-pxv4-2wfj com.rabbitmq:amqp-client (Maven) Fixed in 5.33.0 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
Not affected: 2 products
- Red Hat Fuse 7
- Red Hat build of Apache Camel 4 for Quarkus 3
Timeline
- 2026-10-02 Threatist record created from CVE-2026-63337
- 2026-10-03 Alias added: GHSA-6g32-pxv4-2wfj
References
Other 7
- https://github.com/rabbitmq/rabbitmq-java-client/security/advisories/GHSA-6g32-pxv4-2wfj
- https://github.com/rabbitmq/rabbitmq-java-client/pull/2000
- https://github.com/rabbitmq/rabbitmq-java-client/pull/2002
- https://github.com/rabbitmq/rabbitmq-java-client/commit/0032f75f9dc3df847f94b2b85a16119250bf63cb
- https://github.com/rabbitmq/rabbitmq-java-client/commit/9f8e7efd0c648f235dc0e96232ae7efa75ea4fa8
- https://github.com/rabbitmq/rabbitmq-java-client/releases/tag/v5.33.0
- https://github.com/rabbitmq/rabbitmq-java-client
More rabbitmq vulnerabilities
- TI-2026-41154 Improper authentication in rabbitmq-server CVSS 3.1CRITICAL 10.0
- TI-2026-41149 RabbitMQ: UNC SSRF affecting the management UI on Windows CVSS 3.1CRITICAL 10.0
- TI-2026-41158 Resource allocation without limits in rabbitmq-server CVSS 3.1HIGH 7.5
- TI-2026-47695 RabbitMQ: OAuth2 Client Secret Exposed via Unauthenticated JavaScript Endpoint CVSS 4.0HIGH 8.2
- TI-2026-47694 RabbitMQ: JWKS Fetch Ignores HTTP Response Status Code - Signing Key Destruction Causes Authentication DoS CVSS 4.0HIGH 8.2
- TI-2026-47558 RabbitMQ: OAuth2 is_integer(Exp) guard skips token-expiry checks for float exp CVSS 4.0MEDIUM 6.3
Sources
- CVE-2026-63337 · CVE Program
- CVE-2026-63337 · NVD
- FIRST EPSS
- GHSA-6g32-pxv4-2wfj · GitHub Advisory Database · CC BY 4.0
- CVE-2026-63337 · Red Hat security data · CC BY 4.0
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