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CVE-2026-33252

MCP Go SDK Allows Cross-Site Tool Execution for HTTP Servers without Authorizatrion

Published: Mar 23, 2026Updated: Apr 15, 2026 Sources: CVE List NVDCWE-352
NVD MITRE
7.1CVSSHIGH
EPSS Score
0.2%
Top 92.6%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

The Go MCP SDK used Go's standard encoding/json. Prior to version 1.4.1, the Go SDK's Streamable HTTP transport accepted browser-generated cross-site `POST` requests without validating the `Origin` header and without requiring `Content-Type: application/json`. In deployments without Authorization, especially stateless or sessionless configurations, this allows an arbitrary website to send MCP requests to a local server and potentially trigger tool execution. Version 1.4.1 contains a patch for the issue.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:UC:NI:HA:L
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:HIntegrity
High
A:LAvailability
Low
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Weaknesses

CWE-352

Affected Products

go-sdkmodelcontextprotocol
Mixed
AI / ML / ai-agent-tooling
mcp go sdklfprojects
Mixed
AI / ML / notebook-mlops
modelcontextprotocoloss-projectAI / MLaka mcp, model context protocol
lfprojectsoss-projectAI / MLaka mlflow, valkey, model context protocol servers, mcp servers

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Initial Access
View detailed technique mapping

References

https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-89xv-2j6f-qhc8
github.com
https://github.com/modelcontextprotocol/go-sdk/commit/a433a831d6e5d5ac3b9e625a8095aa8eaa040dfc
github.com

Timeline

Published
Mar 23, 2026
Last Updated
Apr 15, 2026

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