Vulnerability in Modelcontextprotocol Java-sdk
CVE-2026-34237
MCP Java SDK is the official Java SDK for Model Context Protocol servers and clients. Prior to versions 1.0.1 and 1.1.1, there is a hardcoded wildcard CORS vulnerability. This issue has been patched in versions 1.0.1 and 1.1.1.
EPSS: 0.000 (1.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
Affected products
- Modelcontextprotocol Java-sdk — versions < 1.0.1, < 1.1.1
Weakness classification (CWE)
References
- https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-hv2w-8mjj-jw22 (x_refsource_CONFIRM)
- https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java#L289 (x_refsource_MISC)
- https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L525 (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-34237?
- CVE-2026-34237 is a medium-severity vulnerability in Modelcontextprotocol Java-sdk, classified under Permissive Cross-domain Policy with Untrusted Domains. CVSS score: 6.1/10. Published 2026-03-31.
- How severe is CVE-2026-34237?
- Medium severity. CVSS v3 base score is 6.1 out of 10.