Vulnerability Report

CVE-2026-34237

RCE

Title: Hardcoded Wildcard CORS Vulnerability in MCP Java SDK

RCE

Proof Of Concept

No public PoC currently indexed for CVE-2026-34237.

CWE Category CWE-942

Published Date Mar 31, 2026

Modified Date Jun 09, 2026

Exploit Status Not Found

Score 6.1 CVSS v3.1

Exploit Probability (EPSS)

0.22%

Vulnerability Summary

CVE-2026-34237: MCP Java SDK is the official Java SDK for Model Context Protocol servers and clients. Prior to versions 0.83.0, 1.0.1, and 1.1.1, there is a hardcoded wildcard CORS vulnerability. This issue has been patched in versions 0.83.0, 1.0.1, and 1.1.1.

Impacted Vendors

lfprojects 1

Reference Links

https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java#L289 https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L525 https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-hv2w-8mjj-jw22

CVSS v3.1

Source Entity [email protected]

Severity MEDIUM

6.1

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

REQUIRED

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

CHANGED

RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns