Medium severity · published Mar 31, 2026
CVE-2026-34237
MCP Java SDK has a Hardcoded Wildcard CORS (Access-Control-Allow-Origin: *)
6.1
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 13% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
JA
java-sdk · modelcontextprotocol
>= 1.0.0, < 1.0.1; >= 1.1.0, < 1.1.1; < 0.18.3 · source: vendor
MJ
Mcp Java Sdk · Lfprojects
before 1.0.1; 1.1.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34237
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-34237
Patch
https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java#L289
Patch
https://github.com/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java#L525
Mitigation
https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-hv2w-8mjj-jw22
More from java-sdk
5.7
CVE-2026-35568
MCP Java-SDK has a DNS Rebinding Vulnerability