CVE-2026-34237: CWE-942: Permissive Cross-domain Policy with Untrusted Domains in modelcontextprotocol java-sdk
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.
AI Analysis
Technical Summary
CVE-2026-34237 describes a vulnerability in the MCP Java SDK where a hardcoded wildcard CORS policy permits cross-domain requests from untrusted domains. This permissive cross-domain policy can lead to unauthorized access or data leakage across domains. The vulnerability affects versions prior to 0.83.0, 1.0.1, and 1.1.1 and has been fixed in these versions. The CVSS 3.1 base score is 6.1, indicating a medium severity with network attack vector, low attack complexity, no privileges required, user interaction required, scope changed, and low confidentiality and integrity impact without availability impact.
Potential Impact
The vulnerability allows potentially malicious web domains to bypass same-origin policy restrictions due to the wildcard CORS configuration, which can lead to unauthorized access to sensitive data or actions within the affected MCP Java SDK applications. The impact is limited to confidentiality and integrity with no availability impact. No known exploits are reported in the wild at this time.
Mitigation Recommendations
Upgrade to MCP Java SDK versions 0.83.0, 1.0.1, or 1.1.1 or later, where the hardcoded wildcard CORS vulnerability has been patched. No other mitigation is necessary once the SDK is updated.
CVE-2026-34237: CWE-942: Permissive Cross-domain Policy with Untrusted Domains in modelcontextprotocol java-sdk
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 v3.1
Score 6.1medium
Affected software
pkg:maven/io.modelcontextprotocol/java-sdkRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-34237 describes a vulnerability in the MCP Java SDK where a hardcoded wildcard CORS policy permits cross-domain requests from untrusted domains. This permissive cross-domain policy can lead to unauthorized access or data leakage across domains. The vulnerability affects versions prior to 0.83.0, 1.0.1, and 1.1.1 and has been fixed in these versions. The CVSS 3.1 base score is 6.1, indicating a medium severity with network attack vector, low attack complexity, no privileges required, user interaction required, scope changed, and low confidentiality and integrity impact without availability impact.
Potential Impact
The vulnerability allows potentially malicious web domains to bypass same-origin policy restrictions due to the wildcard CORS configuration, which can lead to unauthorized access to sensitive data or actions within the affected MCP Java SDK applications. The impact is limited to confidentiality and integrity with no availability impact. No known exploits are reported in the wild at this time.
Mitigation Recommendations
Upgrade to MCP Java SDK versions 0.83.0, 1.0.1, or 1.1.1 or later, where the hardcoded wildcard CORS vulnerability has been patched. No other mitigation is necessary once the SDK is updated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-03-26T16:22:29.034Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 69cbedf2e6bfc5ba1d248101
Added to database: 03/31/2026, 15:53:22 UTC
Last enriched: 06/10/2026, 09:29:21 UTC
Last updated: 07/31/2026, 19:22:58 UTC
Views: 138
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