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Advisory record · GHSA-89xv-2j6f-qhc8

Cross-Site Tool Execution for HTTP Servers without Authorizatrion in github.com/modelcontextprotocol/go-sdk

CVSS 7.1 HighEPSS 0.0019 · 8th percentile

Published by the GitHub Advisory Database at 19 Mar 2026, 16:42 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
github.com/modelcontextprotocol/go-sdkGo<1.4.11.4.1
Identifiers
GHSA-89xv-2j6f-qhc8 · CVE-2026-33252 · GO-2026-4773
Weakness (CWE)
CWE-352
Tags
Published
19 Mar 2026
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

The Go SDK github.com/modelcontextprotocol/go-sdk, versions before 1.4.1, accepted cross-site POST requests to its Streamable HTTP transport without checking the Origin header or requiring a JSON Content-Type. A malicious website can send such requests from a visitor's browser to a local server that has no authorization, potentially triggering tool execution. Upgrade to version 1.4.1 or later, which requires Go 1.25 or later.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
7.1 High 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0019, the 8th percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:14 UTC First seen by agentprime
  2. 31 Oct 2026, 14:14 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.