CVE-2026-33252 (GCVE-0-2026-33252)

Vulnerability from cvelistv5 – Published: 2026-03-23 23:44 – Updated: 2026-03-24 18:39
VLAI?
Title
MCP Go SDK Allows Cross-Site Tool Execution for HTTP Servers without Authorizatrion
Summary
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.
Severity ?
7.1 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L
CWE
  • CWE-352 - Cross-Site Request Forgery (CSRF)
Assigner
References
Impacted products
Vendor Product Version
modelcontextprotocol go-sdk Affected: < 1.4.1
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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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