CVE-2026-34237 | MCP Java SDK has a Hardcoded Wildcard CORS (Access-Control-Allow-Origin: *)

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.

Published: 2026-03-31 Last update: 2026-06-09 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-34237 is rated Low Risk (26.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.03%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-34237

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-01 — 0.03% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-34237

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.7 [email protected]

Weakness enumeration for CVE-2026-34237

GitHub Security Advisory for CVE-2026-34237

GHSA-hv2w-8mjj-jw22 · Severity: medium · Ecosystem: maven — MCP Java SDK has a Hardcoded Wildcard CORS (Access-Control-Allow-Origin: *)

Affected software / configurations for CVE-2026-34237

Vendor Product Version Raw CPE
lfprojects mcp_java_sdk < 1.0.1 cpe:2.3:a:lfprojects:mcp_java_sdk:*:*:*:*:*:*:*:*
lfprojects mcp_java_sdk 1.1.0 cpe:2.3:a:lfprojects:mcp_java_sdk:1.1.0:*:*:*:*:*:*:*

References for CVE-2026-34237

cvelogic Threat Intelligence