Vulnerability · Published Mar 31, 2026 · Assigned by GitHub_M
CVE-2026-34237MCP Java SDK has a Hardcoded Wildcard CORS (Access-Control-Allow-Origin: *)
Medium 6.1
In plain English
A medium-severity security flaw in java-sdk from modelcontextprotocol. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 14% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)6.1Medium
Exploit odds (30 days)0.2%top 86.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Maven | io.modelcontextprotocol.sdk:mcp-core | 1.0.1 | GHSA-hv2w-8mjj-jw22 |
| Maven | io.modelcontextprotocol.sdk:mcp-core | 1.1.1 | GHSA-hv2w-8mjj-jw22 |
| Maven | io.modelcontextprotocol.sdk:mcp-core | 0.18.3 | GHSA-hv2w-8mjj-jw22 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| modelcontextprotocol | java-sdk | >= 1.0.0, < 1.0.1>= 1.1.0, < 1.1.1< 0.18.3 |
Weakness: CWE-942 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
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