CVE-2026-33252Network attack vector

Cross-site tool execution via unvalidated POST requests

Published Mar 23, 2026 · Updated Mar 23, 2026

CSRF in Model Context Protocol Go SDK before 1.4.1 allows remote attackers to invoke MCP tools through cross-site POST requests. The StreamableHTTPHandler passes text/plain POST bodies into MCP message handling without checking Origin or requiring application/json. Exploitation requires a victim's browser to visit an attacker-controlled site and an HTTP server lacking authorization; exposed tools can then run with the server's privileges.

CVSS severity7.1
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CSRF in Model Context Protocol Go SDK before 1.4.1 allows remote attackers to invoke MCP tools through cross-site POST requests. The StreamableHTTPHandler passes text/plain POST bodies into MCP message handling without checking Origin or requiring application/json. Exploitation requires a victim's browser to visit an attacker-controlled site and an HTTP server lacking authorization; exposed tools can then run with the server's privileges.

The record

CVE
CVE-2026-33252
Published
Mar 23, 2026
Updated
Mar 23, 2026
Vendor
Model Context Protocol
Product
Go SDK
Classifications
CWE-352, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Model Context Protocol · Go SDKversion=< 1.4.1

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
7.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-352Cross-Site Request Forgery (CSRF)
T1204.001User Execution: Malicious Link

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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