What is CVE-2026-33252?

CVE-2026-33252 is a high-severity vulnerability in Modelcontextprotocol Go-sdk, classified under Cross-Site Request Forgery (CSRF). CVSS score: 7.1/10. Published 2026-03-23.

How severe is CVE-2026-33252?

High severity. CVSS v3 base score is 7.1 out of 10.

CSRF in Modelcontextprotocol Go-sdk

CVE-2026-33252

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-Typ…

Vulnerability class: CSRF (Cross-Site Request Forgery)

EPSS: 0.000 (0.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L.

Affected products

Modelcontextprotocol Go-sdk — versions < 1.4.1

Weakness classification (CWE)

CWE-352 — Cross-Site Request Forgery (CSRF)

References

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

Frequently asked questions

What is CVE-2026-33252?: CVE-2026-33252 is a high-severity vulnerability in Modelcontextprotocol Go-sdk, classified under Cross-Site Request Forgery (CSRF). CVSS score: 7.1/10. Published 2026-03-23.
How severe is CVE-2026-33252?: High severity. CVSS v3 base score is 7.1 out of 10.