How severe is CVE-2026-33252?

CVE-2026-33252 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability low.

Is CVE-2026-33252 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33252?

CVE-2026-33252 affects Lfprojects Mcp Go Sdk. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33252?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-33252 have an EU (EUVD) identifier?

Yes. CVE-2026-33252 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-14643.

When was CVE-2026-33252 published?

CVE-2026-33252 was published on 2026-03-24 and last updated on 2026-06-17.

CVE-2026-33252

CVE-2026-33252 is a high-severity vulnerability in Lfprojects Mcp Go Sdk with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-352.

Key facts

Severity: High (CVSS 3.x base score 7.1)
EPSS exploit prediction: 0% (7th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-14643
Weakness: CWE-352
Affected product: Lfprojects Mcp Go Sdk
Published: 2026-03-24
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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-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.
How severe is CVE-2026-33252?: CVE-2026-33252 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability low.
Is CVE-2026-33252 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33252?: CVE-2026-33252 affects Lfprojects Mcp Go Sdk. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33252?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-33252 have an EU (EUVD) identifier?: Yes. CVE-2026-33252 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-14643.
When was CVE-2026-33252 published?: CVE-2026-33252 was published on 2026-03-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:lfprojects:mcp_go_sdk:*:*:*:*:*:*:*:*

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