CVE-2026-63337

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 75% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this weekElevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
50(Track*)
EG Risk 50/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
0%
EPSS %ILE
25%
KEV
Not listed

Published

August 18, 2026

Last Modified

August 18, 2026

Advisory Details (6)

Auto-updated Aug 18, 2026
Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available

5.33.0

Patch available: rabbitmq/rabbitmq-java-client v5.33.0

https://github.com/rabbitmq/rabbitmq-java-client/releases/tag/v5.33.0
github_commit

commit 9f8e7efd0c64 (rabbitmq/rabbitmq-java-client)

Fix landed in rabbitmq/rabbitmq-java-client commit 9f8e7efd0c64 — awaiting tagged release

https://github.com/rabbitmq/rabbitmq-java-client/commit/9f8e7efd0c648f235dc0e96232ae7efa75ea4fa8
github_commit Patch Available

commit 0032f75f9dc3 (rabbitmq/rabbitmq-java-client)

Patch available: rabbitmq/rabbitmq-java-client v5.33.0 (contains commit 0032f75f9dc3)

https://github.com/rabbitmq/rabbitmq-java-client/commit/0032f75f9dc3df847f94b2b85a16119250bf63cb
github_pr Patch Available

Harden RPC support classes (backport #2000)

Patch available: rabbitmq/rabbitmq-java-client v5.33.0 (PR #2002 merged 2026-06-30)

https://github.com/rabbitmq/rabbitmq-java-client/pull/2002
github_pr

Harden RPC support classes

Fix merged in rabbitmq/rabbitmq-java-client PR #2000 on 2026-06-29 — awaiting tagged release

https://github.com/rabbitmq/rabbitmq-java-client/pull/2000
github Patch Available

Unvalidated Class.forName in JSON-RPC ProcedureDescription enables arbitrary class loading · Advisory · rabbitmq/rabbitmq-java-client · GitHub

https://github.com/rabbitmq/rabbitmq-java-client/security/advisories/GHSA-6g32-pxv4-2wfj

Vendor Advisories for CVE-2026-63337(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 9× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-20 23:25 UTCEG score recompute
  2. 2026-08-20 22:55 UTCEPSS rescore
  3. 2026-08-19 21:55 UTCEG score recompute
  4. 2026-08-19 17:04 UTCEPSS rescore
  5. 2026-08-18 20:23 UTCEG score recompute
  6. 2026-08-18 19:19 UTCEG score recompute
  7. 2026-08-18 17:21 UTCEG score recompute
  8. 2026-08-18 16:35 UTCEG score recompute
  9. 2026-08-18 16:34 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-63337?
CVE-2026-63337 is a high vulnerability published on August 18, 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,…
When was CVE-2026-63337 disclosed?
CVE-2026-63337 was first published in the National Vulnerability Database on August 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63337 actively exploited?
CVE-2026-63337 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 75.4% of all scored CVEs.
What is the CVSS score of CVE-2026-63337?
CVE-2026-63337 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-63337?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63337, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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