CVE-2026-34237 json
MCP Java SDK has a Hardcoded Wildcard CORS (Access-Control-Allow-Origin: *)
published 2026-03-30 7 mo ago modified 2026-09-10 1 mo ago also GHSA-hv2w-8mjj-jw22 , EUVD-2026-17496
- cvss
- 6.1
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 14%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- maven io.modelcontextprotocol.sdk:mcp-core 0.18.3, 1.0.1, 1.1.1
- lfprojects mcp_java_sdk 1.0.1
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 7 mo ago
Exploit prediction
0.23% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| GitHub | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| maven | io.modelcontextprotocol.sdk:mcp-core | >=1.0.0, <1.0.1 >=1.1.0, <1.1.1 <0.18.3 |
1.0.1 1.1.1 0.18.3 |
Affected products
- modelcontextprotocol java-sdk
Classification
- Weakness
-
- CWE-942 Permissive Cross-domain Security Policy with Untrusted Domains
References
-
github.com
/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpS
web, patch
-
github.com
/modelcontextprotocol/java-sdk/blob/main/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpS
web, patch
-
github.com
/modelcontextprotocol/java-sdk/security/advisories/GHSA-hv2w-8mjj-jw22
web, mitigation, vendor-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-34237
advisory
-
cheatsheetseries.owasp.org
/cheatsheets/HTTP_Headers_Cheat_Sheet.html#access-control-allow-origin
web
-
github.com
/modelcontextprotocol/java-sdk
package
Sources
- CVE List CVE-2026-34237
- GitHub Advisory GHSA-hv2w-8mjj-jw22
- NVD CVE-2026-34237
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